The 100 most-cited articles in The Astrophysical Journal, 2024

Abstract Characterizing the prevalence and properties of faint active galactic nuclei (AGNs) in the early Universe is key for understanding the formation of supermassive black holes (SMBHs) and determining their role in cosmic reionization. We perform a spectroscopic search for broad H α emitters at z ≈ 4–6 using deep JWST/NIRCam imaging and wide field slitless spectroscopy from the EIGER and FRESCO surveys. We identify 20 H α lines at z = 4.2–5.5 that have broad components with line widths from ∼1200–3700 km s −1 , contributing ∼30%–90% of the total line flux. We interpret these broad components as being powered by accretion onto SMBHs with implied masses ∼10 7–8 M ⊙ . In the UV luminosity range M UV,AGN+host = −21 to −18, we measure number densities of ≈10 −5 cMpc −3 . This is an order of magnitude higher than expected from extrapolating quasar UV luminosity functions (LFs). Yet, such AGN are found in only <1% of star-forming galaxies at z ∼ 5. The number density discrepancy is much lower when compared to the broad H α LF. The SMBH mass function agrees with large cosmological…

Abstract The James Webb Space Telescope is revealing a new population of dust-reddened broad-line active galactic nuclei (AGN) at redshifts z ≳ 5. Here we present deep NIRSpec/Prism spectroscopy from the Cycle 1 Treasury program Ultradeep NIRSpec and NIRCam ObserVations before the Epoch of Reionization (UNCOVER) of 15 AGN candidates selected to be compact, with red continua in the rest-frame optical but with blue slopes in the UV. From NIRCam photometry alone, they could have been dominated by dusty star formation or an AGN. Here we show that the majority of the compact red sources in UNCOVER are dust-reddened AGN: 60% show definitive evidence for broad-line H α with a FWHM > 2000 km s −1 , 20% of the current data are inconclusive, and 20% are brown dwarf stars. We propose an updated photometric criterion to select red z > 5 AGN that excludes brown dwarfs and is expected to yield >80% AGN. Remarkably, among all z phot > 5 galaxies with F277W – F444W > 1 in UNCOVER at least 33% are AGN regardless of compactness, climbing to at least 80% AGN for sources with F277W – F444W > 1.6. The…

Abstract We present cosmological constraints from a gravitational lensing mass map covering 9400 deg 2 reconstructed from measurements of the cosmic microwave background (CMB) made by the Atacama Cosmology Telescope (ACT) from 2017 to 2021. In combination with measurements of baryon acoustic oscillations and big bang nucleosynthesis, we obtain the clustering amplitude σ 8 = 0.819 ± 0.015 at 1.8% precision, S 8 ≡ σ 8 ( Ω m / 0.3 ) 0.5 = 0.840 ± 0.028 , and the Hubble constant H 0 = (68.3 ± 1.1) km s −1 Mpc −1 at 1.6% precision. A joint constraint with Planck CMB lensing yields σ 8 = 0.812 ± 0.013, S 8 ≡ σ 8 ( Ω m / 0.3 ) 0.5 = 0.831 ± 0.023 , and H 0 = (68.1 ± 1.0) km s −1 Mpc −1 . These measurements agree with ΛCDM extrapolations from the CMB anisotropies measured by Planck. We revisit constraints from the KiDS, DES, and HSC galaxy surveys with a uniform set of assumptions and find that S 8 from all three are lower than that from ACT+Planck lensing by levels ranging from 1.7 σ to 2.1 σ . This motivates further measurements and comparison, not just between the CMB anisotropies and…

Abstract We present new measurements of cosmic microwave background (CMB) lensing over 9400 deg 2 of the sky. These lensing measurements are derived from the Atacama Cosmology Telescope (ACT) Data Release 6 (DR6) CMB data set, which consists of five seasons of ACT CMB temperature and polarization observations. We determine the amplitude of the CMB lensing power spectrum at 2.3% precision (43 σ significance) using a novel pipeline that minimizes sensitivity to foregrounds and to noise properties. To ensure that our results are robust, we analyze an extensive set of null tests, consistency tests, and systematic error estimates and employ a blinded analysis framework. Our CMB lensing power spectrum measurement provides constraints on the amplitude of cosmic structure that do not depend on Planck or galaxy survey data, thus giving independent information about large-scale structure growth and potential tensions in structure measurements. The baseline spectrum is well fit by a lensing amplitude of A lens = 1.013 ± 0.023 relative to the Planck 2018 CMB power spectra best-fit ΛCDM model…

Abstract Observations with the James Webb Space Telescope (JWST) have uncovered numerous faint active galactic nuclei (AGN) at z ∼ 5 and beyond. These objects are key to our understanding of the formation of supermassive black holes (SMBHs), their coevolution with host galaxies, as well as the role of AGN in cosmic reionization. Using photometric colors and size measurements, we perform a search for compact red objects in an array of blank deep JWST/NIRCam fields totaling ∼640 arcmin 2 . Our careful selection yields 260 reddened AGN candidates at 4 < z phot < 9, dominated by a point-source-like central component (〈 r eff 〉 < 130 pc) and displaying a dichotomy in their rest-frame colors (blue UV and red optical slopes). Quasar model fitting reveals our objects to be moderately dust-extincted ( A V ∼ 1.6), which is reflected in their inferred bolometric luminosities of L bol = 10 44–47 erg s −1 and fainter UV magnitudes M UV ≃ −17 to −22. Thanks to the large areas explored, we extend the existing dusty AGN luminosity functions to both fainter and brighter magnitudes, estimating their…

Abstract In 2019 the NICER collaboration published the first mass and radius inferred for PSR J0030+0451, thanks to NICER observations, and consequent constraints on the equation of state characterizing dense matter. Two independent analyses found a mass of ∼1.3–1.4 M ⊙ and a radius of ∼13 km. They also both found that the hot spots were all located on the same hemisphere, opposite to the observer, and that at least one of them had a significantly elongated shape. Here we reanalyze, in greater detail, the same NICER data set, incorporating the effects of an updated NICER response matrix and using an upgraded analysis framework. We expand the adopted models and also jointly analyze XMM-Newton data, which enables us to better constrain the fraction of observed counts coming from PSR J0030+0451. Adopting the same models used in previous publications, we find consistent results, although with more stringent inference requirements. We also find a multimodal structure in the posterior surface. This becomes crucial when XMM-Newton data is accounted for. Including the corresponding…

Abstract We report detections of the [O iii ] λ 4364 auroral emission line for 16 galaxies at z = 2.1–8.7, measured from JWST/NIRSpec observations obtained as part of the Cosmic Evolution Early Release Science (CEERS) survey program. We combine this CEERS sample with 9 objects from the literature at z = 4−9 with auroral-line detections from JWST/NIRSpec and 21 galaxies at z = 1.4−3.7 with auroral-line detections from ground-based spectroscopy. We derive electron temperature ( T e ) and direct-method oxygen abundances for the combined sample of 46 star-forming galaxies at z = 1.4−8.7. We use these measurements to construct the first high-redshift empirical T e -based metallicity calibrations for the strong-line ratios [O iii ]/H β , [O ii ]/H β , R23 = ([O iii ]+[O ii ])/H β , [O iii ]/[O ii ], and [Ne iii ]/[O ii ]. These new calibrations are valid over 12+log(O/H) = 7.4−8.3 and can be applied to samples of star-forming galaxies at z = 2−9, leading to an improvement in the accuracy of metallicity determinations at Cosmic Noon and in the Epoch of Reionization. The high-redshift…

Abstract We report an updated analysis of the radius, mass, and heated surface regions of the massive pulsar PSR J0740+6620 using Neutron Star Interior Composition Explorer (NICER) data from 2018 September 21 to 2022 April 21, a substantial increase in data set size compared to previous analyses. Using a tight mass prior from radio-timing measurements and jointly modeling the new NICER data with XMM-Newton data, the inferred equatorial radius and gravitational mass are 12.49 − 0.88 + 1.28 km and 2.073 − 0.069 + 0.069 M ⊙ , respectively, each reported as the posterior credible interval bounded by the 16% and 84% quantiles, with an estimated systematic error ≲ 0.1 km. This result was obtained using the best computationally feasible sampler settings providing a strong radius lower limit but a slightly more uncertain radius upper limit. The inferred radius interval is also close to the R = 12.76 − 1.02 + 1.49 km obtained by Dittmann et al., when they require the radius to be less than 16 km as we do. The results continue to disfavor very soft equations of state for dense matter, with R…

Abstract We study 31 little red dots (LRD) detected by JADES/NIRCam and covered by the SMILES/MIRI survey, of which ∼70% are detected in the two bluest MIRI bands and 40% in redder MIRI filters. The median/quartiles redshifts are z = 6.9 5.9 7.7 (55% spectroscopic). The spectral slopes flatten in the rest-frame near-infrared, consistent with a 1.6 μm stellar bump but bluer than direct pure emission from active galactic nuclei (AGN) tori. The apparent dominance of stellar emission at these wavelengths for many LRDs expedites stellar mass estimation: the median/quartiles are log M ⋆ / M ⊙ = 9.4 9.1 9.7 . The number density of LRDs is 10−4.0±0.1 Mpc−3, accounting for 14% ± 3% of the global population of galaxies with similar redshifts and masses. The rest-frame near-/mid-infrared (2–4 μm) spectral slope reveals significant amounts of warm dust (bolometric attenuation ∼3–4 mag). Our spectral energy distribution modeling implies the presence of <0.4 kpc diameter knots, heated by either dust-enshrouded OB stars or an AGN producing a similar radiation field, obscured by A(V) > 10 mag. We…

Abstract We spectroscopically confirm the M UV = −20.5 mag galaxy GHZ2/GLASS-z12 to be at redshift z = 12.34. The source was selected via NIRCam photometry in GLASS-JWST Early Release Science data, providing the first evidence of a surprising abundance of bright galaxies at z ≳ 10. The NIRSpec PRISM spectrum shows detections of N iv , C iv , He ii , O iii , C iii , O ii , and Ne iii lines and the first detection at high redshift of the O iii Bowen fluorescence line at 3133 Å rest frame. The prominent C iv line with rest-frame equivalent width (EW) ≈ 46 Å puts GHZ2 in the category of extreme C iv emitters. GHZ2 displays UV lines with EWs that are only found in active galactic nuclei (AGNs) or composite objects at low/intermediate redshifts. The UV line-intensity ratios are compatible with both AGNs and star formation in a low-metallicity environment, with the low limit on the [Ne iv ]/[N iv ] ratio favoring a stellar origin of the ionizing photons. We discuss a possible scenario in which the high ionizing output is due to low-metallicity stars forming in a dense environment. We…

Abstract Using deep JWST imaging from JADES, JEMS, and SMILES, we characterize optically faint and extremely red galaxies at z > 3 that were previously missing from galaxy census estimates. The data indicate the existence of abundant, dusty, and poststarburst-like galaxies down to 10 8 M ⊙ , below the sensitivity limit of Spitzer and the Atacama Large Millimeter/submillimeter Array (ALMA). Modeling the NIRCam and Hubble Space Telescope (HST) photometry of these red sources can result in extremely high values for both stellar mass and star formation rate (SFR); however, including seven MIRI filters out to 21 μ m results in decreased masses (median 0.6 dex for log 10 ( M ∗ / M ⊙ ) > 10) and SFRs (median 10× for SFR > 100 M ⊙ yr −1 ). At z > 6, our sample includes a high fraction of “little red dots” (LRDs; NIRCam-selected dust-reddened active galactic nucleus (AGN) candidates). We significantly measure older stellar populations in the LRDs out to rest-frame 3 μ m (the stellar bump) and rule out a dominant contribution from hot dust emission, a signature of AGN contamination to stellar…

Abstract We present a catalog of 717 candidate galaxies at z > 8 selected from 125 square arcmin of NIRCam imaging as part of the JWST Advanced Deep Extragalactic Survey (JADES). We combine the full JADES imaging data set with data from the JWST Extragalactic Medium Survey and First Reionization Epoch Spectroscopic COmplete Survey (FRESCO) along with extremely deep existing observations from Hubble Space Telescope (HST)/Advanced Camera for Surveys (ACS) for a final filter set that includes 15 JWST/NIRCam filters and five HST/ACS filters. The high-redshift galaxy candidates were selected from their estimated photometric redshifts calculated using a template-fitting approach, followed by visual inspection from seven independent reviewers. We explore these candidates in detail, highlighting interesting resolved or extended sources, sources with very red long-wavelength slopes, and our highest-redshift candidates, which extend to z phot ∼ 18. Over 93% of the sources are newly identified from our deep JADES imaging, including 31 new galaxy candidates at z phot > 12. We also investigate…

Abstract The James Webb Space Telescope (JWST) is revolutionizing our knowledge of z > 5 galaxies and their actively accreting black holes. Using the JWST Cycle 1 Treasury program Ultradeep NIRSpec and NIRCam Observations before the Epoch of Reionization (UNCOVER) in the lensing field A2744, we report the identification of a sample of little red dots at 3 < z phot < 7 that likely contain highly reddened accreting supermassive black holes. Using a NIRCam-only selection to F444W < 27.7 mag, we find 26 sources over the ∼45 arcmin 2 field that are blue in F115W − F200W ∼ 0 (or β UV ∼ –2.0 for f λ ∝ λ β ), red in F200W − F444W = 1−4 ( β opt ∼ +2.0), and are dominated by a point-source-like central component. Of the 20 sources with deep Atacama Large Millimeter/submillimeter Array (ALMA) 1.2 mm coverage, none are detected individually or in a stack. For the majority of the sample, spectral energy distribution fits to the JWST+ALMA observations prefer models with hot dust rather than obscured star formation to reproduce the red NIRCam colors and ALMA 1.2 mm nondetections. While compact…

Abstract In this paper we describe the survey design for the Ultradeep NIRSpec and NIRCam Observations before the Epoch of Reionization (UNCOVER) Cycle 1 JWST Treasury program, which executed its early imaging component in 2022 November. The UNCOVER survey includes ultradeep (∼29–30AB) imaging of ∼45 arcmin2 on and around the well-studied A2744 galaxy cluster at z = 0.308 and will follow up ∼500 galaxies with extremely deep low-resolution spectroscopy with the NIRSpec/PRISM during the summer of 2023, with repeat visits in summer 2024. We describe the science goals, survey design, target selection, and planned data releases. We also present and characterize the depths of the first NIRCam imaging mosaic, highlighting previously unparalleled resolved and ultradeep 2–4 μm imaging of known objects in the field. The UNCOVER primary NIRCam mosaic spans 28.8 arcmin2 in seven filters (F115W, F150W, F200W, F277W, F356W, F410M, and F444W) and 16.8 arcmin2 in our NIRISS parallel (F115W, F150W, F200W, F356W, and F444W). To maximize early community use of the Treasury data set, we publicly…

Abstract We study a new population of extremely red objects (EROs) recently discovered by the James Webb Space Telescope (JWST) based on their NIRCam colors F277W − F444W > 1.5 mag. We find 37 EROs in the Cosmic Evolution Early Release Science Survey (CEERS) field with F444W < 28 mag and photometric redshifts between 5 < z < 7, with median z = 6.9 − 1.6 + 1.0 . Surprisingly, despite their red long-wavelength colors, these EROs have blue short-wavelength colors (F150W − F200W ∼ 0 mag) indicative of bimodal spectral energy distributions (SEDs) with a red, steep slope in the rest-frame optical, and a blue, flat slope in the rest-frame UV. Moreover, all these EROs are unresolved, point-like sources in all NIRCam bands. We analyze the SEDs of eight of them with MIRI and NIRSpec observations using stellar population models and active galactic nucleus (AGN) templates. We find that dusty galaxies or obscured AGNs provide similarly good SED fits but different stellar properties: massive and dusty, log M ⋆ / M ⊙ ∼ 10 and A V ≳ 3 mag, or low mass and obscured, log M ⋆ / M ⊙ ∼ 7.5 and A V ∼ 0…

Abstract We characterize the earliest galaxy population in the JADES Origins Field, the deepest imaging field observed with JWST. We make use of ancillary Hubble Space Telescope optical images (five filters spanning 0.4–0.9 μ m) and novel JWST images with 14 filters spanning 0.8−5 μ m, including seven medium-band filters, and reaching total exposure times of up to 46 hr per filter. We combine all our data at >2.3 μ m to construct an ultradeep image, reaching as deep as ≈31.4 AB mag in the stack and 30.3–31.0 AB mag (5 σ , r = 0.″1 circular aperture) in individual filters. We measure photometric redshifts and use robust selection criteria to identify a sample of eight galaxy candidates at redshifts z = 11.5−15. These objects show compact half-light radii of R 1/2 ∼ 50−200 pc, stellar masses of M ⋆ ∼ 10 7 −10 8 M ☉ , and star formation rates ∼ 0.1−1 M ☉ yr −1 . Our search finds no candidates at 15 < z < 20, placing upper limits at these redshifts. We develop a forward-modeling approach to infer the properties of the evolving luminosity function without binning in redshift or…

Abstract We present phase-corrected photometric measurements of 88 Cepheid variables in the core of the Small Magellanic Cloud (SMC), the first sample obtained with the Hubble Space Telescope's (HST) Wide Field Camera 3, in the same homogeneous photometric system as past measurements of all Cepheids on the SH0ES distance ladder. We limit the sample to the inner core and model the geometry to reduce errors in prior studies due to the nontrivial depth of this cloud. Without crowding present in ground-based studies, we obtain an unprecedentedly low dispersion of 0.102 mag for a period–luminosity (P–L) relation in the SMC, approaching the width of the Cepheid instability strip. The new geometric distance to 15 late-type detached eclipsing binaries in the SMC offers a rare opportunity to improve the foundation of the distance ladder, increasing the number of calibrating galaxies from three to four. With the SMC as the only anchor, we find H 0 = 74.1 ± 2.1 km s−1 Mpc−1. Combining these four geometric distances with our HST photometry of SMC Cepheids, we obtain H 0 = 73.17 ± 0.86 km s−1…

Abstract The recent results from the first-year baryon acoustic oscillations (BAO) data released by the Dark Energy Spectroscopic Instrument (DESI), combined with cosmic microwave background (CMB) and Type Ia supernova (SN) data, have shown a detection of significant deviation from a cosmological constant for dark energy. In this work, we utilize the latest DESI BAO data in combination with the SN data from the full 5 yr observations of the Dark Energy Survey and the CMB data from the Planck satellite to explore potential interactions between dark energy and dark matter. We consider four typical forms of the interaction term Q . Our findings suggest that interacting dark energy (IDE) models with Q ∝ ρ de support the presence of an interaction where dark energy decays into dark matter. Specifically, the deviation from ΛCDM for the IDE model with Q = β H 0 ρ de reaches the 3 σ level. These models yield a lower value of Akaike information criterion than the ΛCDM model, indicating a preference for these IDE models based on the current observational data. For IDE models with Q ∝ ρ c ,…

Abstract PSR J0740+6620 is the neutron star with the highest precisely determined mass, inferred from radio observations to be 2.08 ± 0.07 M ⊙. Measurements of its radius therefore hold promise to constrain the properties of the cold, catalyzed, high-density matter in neutron star cores. Previously, Miller et al. and Riley et al. reported measurements of the radius of PSR J0740+6620 based on Neutron Star Interior Composition Explorer (NICER) observations accumulated through 2020 April 17, and an exploratory analysis utilizing NICER background estimates and a data set accumulated through 2021 December 28 was presented in Salmi et al. Here we report an updated radius measurement, derived by fitting models of X-ray emission from the neutron star surface to NICER data accumulated through 2022 April 21, totaling ∼1.1 Ms additional exposure compared to the data set analyzed in Miller et al. and Riley et al., and to data from XMM-Newton observations. We find that the equatorial circumferential radius of PSR J0740+6620 is 12.92 − 1.13 + 2.09 km (68% credibility), a fractional uncertainty…

Abstract We present an analysis of the ultraviolet luminosity function (UV LF) and star formation rate density of distant galaxies (7.5 < z < 13.5) in the “blank” fields of the Prime Extragalactic Areas for Reionization and Lensing Science (PEARLS) survey combined with Early Release Science data from the CEERS, GLASS, and NGDEEP surveys/fields and the first data release of JADES. We use strict quality cuts on EAZY photometric redshifts to obtain a reliable selection and characterization of high-redshift (z > 6.5) galaxies from a consistently processed set of deep, near-infrared imaging. Within an area of 180 arcmin2, we identify 1046 candidate galaxies at redshifts z > 6.5 and we use this sample to study the UV LF in four redshift bins between 7.5 < z < 13.5. The measured number density of galaxies at z = 8 and z = 9 matches those of past observations undertaken by the Hubble Space Telescope (HST). Our z = 10.5 measurements lie between early James Webb Space Telescope (JWST) results and past HST results, indicating cosmic variance may be the cause of previous high density…

Abstract We report the discovery of 15 exceptionally luminous 10 ≲ z ≲ 14 candidate galaxies discovered in the first 0.28 deg2 of JWST/NIRCam imaging from the COSMOS-Web survey. These sources span rest-frame UV magnitudes of −20.5 > M UV > −22, and thus constitute the most intrinsically luminous z ≳ 10 candidates identified by JWST to date. Selected via NIRCam imaging, deep ground-based observations corroborate their detection and help significantly constrain their photometric redshifts. We analyze their spectral energy distributions using multiple open-source codes and evaluate the probability of low-redshift solutions; we conclude that 12/15 (80%) are likely genuine z ≳ 10 sources and 3/15 (20%) likely low-redshift contaminants. Three of our z ∼ 12 candidates push the limits of early stellar mass assembly: they have estimated stellar masses ∼ 5 × 109 M ⊙, implying an effective stellar baryon fraction of ϵ ⋆ ∼ 0.2−0.5, where ϵ ⋆ ≡ M ⋆/(f b M halo). The assembly of such stellar reservoirs is made possible due to rapid, burst-driven star formation on timescales < 100 Myr where the…

Abstract We present the full Hubble diagram of photometrically classified Type Ia supernovae (SNe Ia) from the Dark Energy Survey supernova program (DES-SN). DES-SN discovered more than 20,000 SN candidates and obtained spectroscopic redshifts of 7000 host galaxies. Based on the light-curve quality, we select 1635 photometrically identified SNe Ia with spectroscopic redshift 0.10 < z < 1.13, which is the largest sample of supernovae from any single survey and increases the number of known z > 0.5 supernovae by a factor of 5. In a companion paper, we present cosmological results of the DES-SN sample combined with 194 spectroscopically classified SNe Ia at low redshift as an anchor for cosmological fits. Here we present extensive modeling of this combined sample and validate the entire analysis pipeline used to derive distances. We show that the statistical and systematic uncertainties on cosmological parameters are σ Ω M , stat + sys Λ CDM = 0.017 in a flat ΛCDM model, and ( σ Ω M , σ w ) stat + sys w CDM = (0.082, 0.152) in a flat w CDM model. Combining the DES SN data with the…

Abstract The Australian, Chinese, European, Indian, and North American pulsar timing array (PTA) collaborations recently reported, at varying levels, evidence for the presence of a nanohertz gravitational-wave background (GWB). Given that each PTA made different choices in modeling their data, we perform a comparison of the GWB and individual pulsar noise parameters across the results reported from the PTAs that constitute the International Pulsar Timing Array (IPTA). We show that despite making different modeling choices, there is no significant difference in the GWB parameters that are measured by the different PTAs, agreeing within 1 σ . The pulsar noise parameters are also consistent between different PTAs for the majority of the pulsars included in these analyses. We bridge the differences in modeling choices by adopting a standardized noise model for all pulsars and PTAs, finding that under this model there is a reduction in the tension in the pulsar noise parameters. As part of this reanalysis, we “extended” each PTA’s data set by adding extra pulsars that were not timed by…

Abstract The Ultraviolet Transient Astronomy Satellite (ULTRASAT) is scheduled to be launched to geostationary orbit in 2027. It will carry a telescope with an unprecedentedly large field of view (204 deg2) and near-ultraviolet (NUV; 230–290 nm) sensitivity (22.5 mag, 5σ, at 900 s). ULTRASAT will conduct the first wide-field survey of transient and variable NUV sources and will revolutionize our ability to study the hot transient Universe. It will explore a new parameter space in energy and timescale (months-long light curves with minutes cadence), with an extragalactic volume accessible for the discovery of transient sources that is >300 times larger than that of the Galaxy Evolution Explorer (GALEX) and comparable to that of the Vera Rubin Observatory’s Legacy Survey of Space and Time. ULTRASAT data will be transmitted to the ground in real time, and transient alerts will be distributed to the community in <15 minutes, enabling vigorous ground-based follow up of ULTRASAT sources. ULTRASAT will also provide an all-sky NUV image to >23.5 AB mag, over 10 times deeper than the GALEX…

Abstract We cross-check the Hubble Space Telescope (HST) Cepheid/Type Ia supernova (SN Ia) distance ladder, which yields the most precise local H 0, against early James Webb Space Telescope (JWST) subsamples (∼1/4 of the HST sample) from SH0ES and CCHP, calibrated only with NGC 4258. We find HST Cepheid distances agree well (∼1σ) with all combinations of methods, samples, and telescopes. The comparisons explicitly include the measurement uncertainty of each method in NGC 4258, an oft-neglected but dominant term. Mean differences are ∼0.03 mag, far smaller than the 0.18 mag “Hubble tension.” Combining all measures produces the strongest constraint yet on the linearity of HST Cepheid distances, 0.994 ±0.010, ruling out distance-dependent bias or offset as the source of the tension at ∼7σ. However, current JWST subsamples produce large sampling differences in H0 whose size and direction we can directly estimate from the full HST set. We show that ΔH 0 ∼ 2.5 km s−1 Mpc−1 between the CCHP JWST program and the full HST sample is entirely consistent with differences in sample selection. We…

Abstract The first JWST spectroscopy of the luminous galaxy GN-z11 simultaneously established its redshift at z = 10.6 and revealed a rest-ultraviolet spectrum dominated by signatures of highly ionized nitrogen, which has so far defied clear interpretation. We present a reappraisal of this spectrum in the context of both detailed nebular modeling and nearby metal-poor reference galaxies. The N iv ] emission enables the first nebular density measurement in an apparently predominantly star-forming galaxy at z > 10, revealing evidence for extremely high densities n e ≳ 10 5 cm −3 . With a suite of photoionization models, we establish that regardless of the ionization mechanism and accounting for depletion and this density enhancement, gas substantially enriched in nitrogen ([N/O] = +0.52 assuming the nebular emission is dominated by star formation) is required to reproduce the observed lines. We compare the GN-z11 spectrum to local UV databases and highlight a unique nearby galaxy, Mrk 996, where a high concentration of Wolf–Rayet stars and their CNO-processed ejecta produce a UV…

Abstract We present a comprehensive search and analysis of high-redshift galaxies in a suite of nine public JWST extragalactic fields taken in Cycle 1, covering a total effective search area of ∼ 358 arcmin 2 . Through conservative (8 σ ) photometric selection, we identify 341 galaxies at 5 < z < 14, with 109 having spectroscopic redshift measurements from the literature, including recent JWST NIRSpec observations. Our regression analysis reveals that the rest-frame UV size–stellar mass relation follows R eff ∝ M * 0.19 ± 0.03 , similar to that of star-forming galaxies at z ∼ 3, but scaled down in size by ∼0.7 dex. We find a much slower rate for the average size evolution over the redshift range, R eff ∝ (1 + z ) −0.4±0.2 , than that derived in the literature. A fraction (∼13%) of our sample galaxies are marginally resolved even in the NIRCam imaging (≲100 pc), located at ≳1.5 σ below the derived size–mass slope. These compact sources exhibit a high star formation surface density Σ SFR > 10 M ⊙ yr −1 kpc −2 , a range in which only <0.01% of the local star-forming galaxy sample is…

Abstract We report JWST/NIRCam measurements of quasar host galaxy emissions and supermassive black hole (SMBH) masses for six quasars at 5.9 < z < 7.1 in the Emission-line galaxies and Intergalactic Gas in the Epoch of Reionization (EIGER) project. We obtain deep NIRCam imaging in the F115W, F200W, and F356W bands, as well as F356W grism spectroscopy of the quasars. We use bright unsaturated stars to construct models of the point-spread functions (PSFs) and estimate the errors of these PSFs. We then measure or constrain the fluxes and morphology of the quasar host galaxies by fitting the quasar images as a point source plus an exponential disk. We successfully detect the host galaxies of three quasars, which have host-to-quasar-flux ratios of ∼1%–5%. Spectral energy distribution fitting suggests that these quasar host galaxies have stellar masses of M * ≳ 10 10 M ⊙ . For quasars with host galaxy nondetections, we estimate the upper limits of their stellar masses. We use the grism spectra to measure the H β line profile and the continuum luminosity, then estimate the SMBH masses for…

Abstract We present a new grid of cloudy atmosphere and evolution models for substellar objects. These models include the effect of refractory cloud species, including silicate clouds, on the spectra and evolution. We include effective temperatures from 900 to 2400 K and surface gravities from log g = 3.5 to 5.5, appropriate for a broad range of objects with masses between 1 and 84 M J. Model pressure–temperature structures are calculated assuming radiative–convective and chemical equilibrium. We consider the effect of both clouds and metallicity on the atmospheric structure, resulting spectra, and thermal evolution of substellar worlds. We parameterize clouds using the A. S. Ackerman & M. S. Marley cloud model, including cloud parameter f sed values from 1 to 8; we include three metallicities (−0.5, 0.0, and +0.5). Refractory clouds and metallicity both alter the evolution of substellar objects, changing the inferred temperature at a given age by up to 100–200 K. For solar-metallicity evolution models including clouds in warm objects, we find a hydrogen-burning minimum mass of 70.2…

Abstract Disequilibrium chemistry due to vertical mixing in the atmospheres of many brown dwarfs and giant exoplanets is well established. Atmosphere models for these objects typically parameterize mixing with the highly uncertain K zz diffusion parameter. The role of mixing in altering the abundances of C-N-O-bearing molecules has mostly been explored for atmospheres with a solar composition. However, atmospheric metallicity and the C/O ratio also impact atmospheric chemistry. Therefore, we present the Sonora Elf Owl grid of self-consistent cloud-free 1D radiative-convective equilibrium model atmospheres for JWST observations, which includes a variation in K zz across several orders of magnitude and also encompasses subsolar to supersolar metallicities and C/O ratios. We find that the impact of K zz on the T ( P ) profile and spectra is a strong function of both T eff and metallicity. For metal-poor objects, K zz has large impacts on the atmosphere at significantly higher T eff than in metal-rich atmospheres, where the impact of K zz is seen to occur at lower T eff . We identify…

Abstract We present a systematic analysis of the X-ray emission of a sample of 17 optically selected, X-ray-detected tidal disruption events (TDEs) discovered between 2014 and 2021. The X-ray light curves show a diverse range of temporal behaviors, with most sources not following the expected power-law decline. The X-ray spectra are mostly extremely soft and consistent with thermal emission from the innermost region of an accretion disk, which cools as the accretion rate decreases. Three sources show formation of a hard X-ray corona at late times. The spectral energy distribution shape, probed by the ratio (L BB/L X) between the UV/optical and X-ray, shows a wide range of L BB/L X ∈ (0.5, 3000) at early times and converges to disklike values of L BB/L X ∈ (0.5, 10) at late times. We estimate the fraction of optically discovered TDEs with L X ≥ 1042 erg s−1 to be at least 40% and show that X-ray loudness is independent of black hole mass. We argue that distinct disk formation timescales are unlikely to be able to explain the diverse range of X-ray evolution. We combine our sample…

Abstract We present volume-averaged neutral hydrogen fractions x H I and ionized bubble radii R b measured with Ly α damping wing absorption of galaxies at the epoch of reionization. We combine JWST/NIRSpec spectra taken by the CEERS, GO-1433, DDT-2750, and JADES programs and obtain a sample containing 27 bright UV-continuum ( M UV < −18.5 mag) galaxies at 7 < z < 12. We construct four composite spectra binned by redshift and find the clear evolution of the softening break toward high redshift at rest-frame 1216 Å, suggesting an increase of Ly α damping wing absorption. We estimate Ly α damping wing absorption in the galaxy spectra with realistic templates including Ly α emission and circumgalactic medium absorptions. Assuming the standard inside-out reionization picture having an ionized bubble with radius R b around a galaxy embedded in the intergalactic medium with x H I , we obtain x H I ( R b ) values generally increasing (decreasing) from x H I = 0.53 − 0.47 + 0.18 to 0.92 − 0.10 + 0.08 ( log R b = 1.67 − 0.16 + 0.14 to − 0.69 − 0.24 + 0.89 comoving Mpc) at redshift 7.12 −…

Abstract Recent constraints on neutron star mass and radius have advanced our understanding of the equation of state (EOS) of cold dense matter. Some of them have been obtained by modeling the pulses of three millisecond X-ray pulsars observed by the Neutron Star Interior Composition Explorer (NICER). Here, we present a Bayesian parameter inference for a fourth pulsar, PSR J1231−1411, using the same technique with NICER and XMM-Newton data. When applying a broad mass-inclination prior from radio timing measurements and the emission region geometry model that can best explain the data, we find likely converged results only when using a limited radius prior. If limiting the radius to be consistent with the previous observational constraints and EOS analyses, we infer the radius to be 12.6 ± 0.3 km and the mass to be 1.04 − 0.03 + 0.05 M ⊙, each reported as the posterior credible interval bounded by the 16% and 84% quantiles. If using an uninformative prior but limited between 10 and 14 km, we find otherwise similar results, but R eq = 13.5 − 0.5 + 0.3 km for the radius. In both cases,…

Abstract Understanding the coevolution of supermassive black holes and their host systems requires a comprehensive census of active galactic nuclei (AGNs) behavior across a wide range of redshift, luminosity, obscuration level, and galaxy properties. We report significant progress with JWST toward this goal from the Systematic Mid-infrared Instrument Legacy Extragalactic Survey (SMILES). Based on comprehensive spectral energy distribution (SED) analysis of 3273 MIRI-detected sources, we identify 217 AGN candidates over a survey area of ∼34 arcmin 2 , including a primary sample of 111 AGNs in normal massive galaxies ( M * > 10 9.5 M ☉ ) at z ∼ 0–4, an extended sample of 86 AGN candidates in low-mass galaxies ( M * < 10 9.5 M ☉ ), and a high- z sample of 20 AGN candidates at z ∼ 4–8.4. Notably, about 80% of our MIRI-selected AGN candidates are new discoveries despite the extensive pre-JWST AGN searches. Even among the massive galaxies where the previous AGN search is believed to be thorough, 34% of the MIRI AGN identifications are new, highlighting the impact of obscuration on…

Abstract JWST has revealed a population of low-luminosity active galactic nuclei at z > 4 in compact, red hosts (the “Little Red Dots,” or LRDs), which are largely undetected in X-rays. We investigate this phenomenon using General Relativistic Radiation Magnetohydrodynamics simulations of super-Eddington accretion onto a supermassive black hole (SMBH) with M • = 10 7 M ⊙ at z ∼ 6, representing the median population; the spectral energy distributions (SEDs) that we obtain are intrinsically X-ray weak. The highest levels of X-ray weakness occur in SMBHs accreting at mildly super-Eddington rates (1.4 < f Edd < 4) with zero spin, viewed at angles >30° from the pole. X-ray bolometric corrections in the observed 2–10 keV band reach ∼10 4 at z = 6, ∼5 times higher than the highest constraint from X-ray stacking. Most SEDs are extraordinarily steep and soft in the X-rays (median photon index Γ = 3.1, mode of Γ = 4.4). SEDs strong in the X-rays have harder spectra with a high-energy bump when viewed near the hot (>10 8 K) and highly relativistic jet, whereas X-ray weak SEDs lack this…

Abstract We present JWST/NIRSpec prism spectroscopy of MACS0647−JD, a triply lensed z ∼ 11 candidate discovered in Hubble Space Telescope imaging and spatially resolved by JWST imaging into two components, A and B. Spectroscopy of component A yields a spectroscopic redshift z = 10.17 based on seven detected emission lines: C iii ] λ λ 1907, 1909, [O ii ] λ 3727, [Ne iii ] λ 3869, [Ne iii ] λ 3968, H δ λ 4101, H γ λ 4340, and [O iii ] λ 4363. These are the second-most distant detections of these emission lines to date, in a galaxy observed just 460 million years after the Big Bang. Based on observed and extrapolated line flux ratios we derive a gas-phase metallicity 12 + log(O/H) ∼ 7.5–8.0, or Z ∼ (0.06–0.2) Z ⊙ , ionization parameter log ( U ) = −1.9 ± 0.2, and an ionizing photon production efficiency log ( ξ ion ) = 25.2 ± 0.2 erg −1 Hz. The spectrum has a softened Ly α break, evidence for a strong Ly α damping wing. The Ly α damping wing also suppresses the F150W photometry, explaining the slightly overestimated photometric redshift z = 10.6 ± 0.3. MACS0647−JD has a stellar mass…

Abstract We present radio observations of 23 optically discovered tidal disruption events (TDEs) on timescales of ∼500–3200 days postdiscovery. We detect nine new TDEs that did not have detectable radio emission at earlier times, indicating a late-time brightening after several hundred (and up to 2300) days; an additional seven TDEs exhibit radio emission whose origin is ambiguous or may be attributed to the host galaxy or an active galactic nucleus. We also report a new rising component in one TDE previously detected in the radio at ∼103 days. While the radio emission in some of the detected TDEs peaked on a timescale ≈2–4 yr, over half of the sample still show rising emission. The range of luminosities for the sample is ∼1037–1039 erg s−1, about 2 orders of magnitude below the radio luminosity of the relativistic TDE Sw J1644+57. Our data set indicates ∼40% of all optical TDEs are detected in radio hundreds to thousands of days after discovery, and that this is probably more common than early radio emission peaking at ∼102 days. Using an equipartition analysis, we find evidence…

Abstract We present a suite of models of the coherent magnetic field of the Galaxy based on new divergence-free parametric functions describing the global structure of the field. The model parameters are fit to the latest full-sky Faraday rotation measures (RMs) of extragalactic sources and polarized synchrotron intensity (PI) maps from the Wilkinson Microwave Anisotropy Probe and Planck. We employ multiple models for the density of thermal and cosmic-ray electrons in the Galaxy, needed to predict the sky maps of RMs and PI for a given Galactic magnetic field (GMF) model. The robustness of the inferred properties of the GMF is gauged by studying many combinations of parametric field models and electron density models. We determine the pitch angle of the local magnetic field (11° ± 1°), explore the evidence for a grand-design spiral coherent magnetic field (inconclusive), determine the strength of the toroidal and poloidal magnetic halo fields below and above the disk (magnitudes the same for both hemispheres within ≈10%), set constraints on the half-height of the cosmic-ray…

Abstract Fast radio bursts (FRBs) are a powerful and mysterious new class of transients that are luminous enough to be detected at cosmological distances. By associating FRBs to host galaxies, we can measure intrinsic and environmental properties that test FRB origin models, in addition to using them as precise probes of distant cosmic gas. The Deep Synoptic Array (DSA-110) is a radio interferometer built to maximize the rate at which it can simultaneously detect and localize FRBs. Here, we present the first sample of FRBs and host galaxies discovered by the DSA-110. This sample of 11 FRBs is the largest, most uniform sample of localized FRBs to date, as it is selected based on association with host galaxies identified in optical imaging by Pan-STARRS1. These FRBs have not been observed to repeat, and their radio properties (dispersion, temporal scattering, energy) are similar to that of the known nonrepeating FRB population. Most host galaxies have ongoing star formation, as has been identified before for FRB hosts. Two hosts of the new sample are massive, quiescent galaxies. The…

Abstract We measure host galaxy stellar masses for a sample of five luminous quasars at z ∼ 5–7. Using JWST/NIRCam medium-band images of nearby point-spread function reference stars, we carefully subtract the contribution from the quasar light to place upper and lower limits on the flux of each host galaxy. We find that the members of our sample of quasar host galaxies have mass upper limits of 10 9.7 –10 10.8 M ⊙ , significantly less than expected from their supermassive black hole (SMBH) masses and the local M BH – M * relation. We additionally obtain JWST/NIRSpec integral field unit spectra of three of our quasars to calculate black hole masses, which we find are consistent with those in the literature, and to search for the presence of bright but compact galaxies via a Balmer break, for which we do not find evidence. We discuss the potential effects of dust extinction on our measured fluxes and the impact of selection effects on high-redshift quasar samples. We conclude that the masses of the SMBHs relative to the host galaxy stellar masses have a much larger scatter than…

Abstract Most tidal disruption events (TDEs) are currently found in time-domain optical and soft X-ray surveys, both of which are prone to significant obscuration. The infrared (IR), however, is a powerful probe of dust-enshrouded environments; hence, we recently performed a systematic search of NEOWISE mid-IR data for nearby, obscured TDEs within roughly 200 Mpc. We identified 18 TDE candidates in galactic nuclei, using difference imaging to uncover nuclear variability among significant host galaxy emission. These candidates were selected based on the following IR light-curve properties: (1) L W2 ≳ 10 42 erg s −1 at peak; (2) fast rise, followed by a slow, monotonic decline; (3) no significant prior variability; and (4) no evidence for active galactic nucleus (AGN) activity in Wide-field Infrared Survey Explorer (WISE) colors. The majority of these sources showed no variable optical counterpart, suggesting that optical surveys indeed miss numerous obscured TDEs. Using narrow-line ionization levels and variability arguments, we identified six sources as possible underlying AGN,…

Abstract The exceptional spectra of the most luminous z > 10 sources observed so far have challenged our understanding of early galaxy evolution, requiring a new observational benchmark for meaningful interpretation. As such, we construct spectroscopic templates representative of high-redshift, star-forming populations, using 482 confirmed sources at z = 5.0−12.9 with JWST/NIRSpec prism observations, and report on their average properties. We find z = 5−11 galaxies are dominated by blue UV continuum slopes ( β = −2.3 to −2.7) and reduced Balmer indices, characteristic of dust-poor and young systems, with a shift towards bluer slopes and younger ages with redshift. The evolution is mirrored by ubiquitous C iii ] detections across all redshifts (rest-frame equivalent widths of 5−14 Å), which increase in strength towards early times. Rest-frame optical lines reveal elevated ratios (O32 = 7–31, R23 = 5–8, and Ne3O2 = 1−2) and subsolar metallicities (log(O/H) = 7.3−7.9), typical of ionization conditions and metallicities rarely observed in z ∼ 0 populations. Within our sample, we…

Abstract Gravitational lensing by massive objects along the line of sight to the source causes distortions to gravitational wave (GW) signals; such distortions may reveal information about fundamental physics, cosmology, and astrophysics. In this work, we have extended the search for lensing signatures to all binary black hole events from the third observing run of the LIGO-Virgo network. We search for repeated signals from strong lensing by (1) performing targeted searches for subthreshold signals, (2) calculating the degree of overlap among the intrinsic parameters and sky location of pairs of signals, (3) comparing the similarities of the spectrograms among pairs of signals, and (4) performing dual-signal Bayesian analysis that takes into account selection effects and astrophysical knowledge. We also search for distortions to the gravitational waveform caused by (1) frequency-independent phase shifts in strongly lensed images, and (2) frequency-dependent modulation of the amplitude and phase due to point masses. None of these searches yields significant evidence for lensing.…

Abstract The JWST Disk Infrared Spectral Chemistry Survey (JDISCS) aims to understand the evolution of the chemistry of inner protoplanetary disks using the Mid-InfraRed Instrument (MIRI) on the James Webb Space Telescope (JWST). With a growing sample of >30 disks, the survey implements a custom method to calibrate the MIRI Medium Resolution Spectrometer (MRS) to contrasts of better than 1:300 across its 4.9–28 μ m spectral range. This is achieved using observations of Themis family asteroids as precise empirical reference sources. The high spectral contrast enables precise retrievals of physical parameters, searches for rare molecular species and isotopologues, and constraints on the inventories of carbon- and nitrogen-bearing species. JDISCS also offers significant improvements to the MRS wavelength and resolving power calibration. We describe the JDISCS calibrated data and demonstrate their quality using observations of the disk around the solar-mass young star FZ Tau. The FZ Tau MIRI spectrum is dominated by strong emission from warm water vapor. We show that the water and CO…

Abstract We present a new, all-sky quasar catalog, Quaia, that samples the largest comoving volume of any existing spectroscopic quasar sample. The catalog draws on the 6,649,162 quasar candidates identified by the Gaia mission that have redshift estimates from the space observatory’s low-resolution blue photometer/red photometer spectra. This initial sample is highly homogeneous and complete, but has low purity, and 18% of even the bright ( G < 20.0) confirmed quasars have discrepant redshift estimates (∣Δ z /(1 + z )∣ > 0.2) compared to those from the Sloan Digital Sky Survey (SDSS). In this work, we combine the Gaia candidates with unWISE infrared data (based on the Wide-field Infrared Survey Explorer survey) to construct a catalog useful for cosmological and astrophysical quasar studies. We apply cuts based on proper motions and colors, reducing the number of contaminants by approximately four times. We improve the redshifts by training a k -Nearest Neighbor model on SDSS redshifts, and achieve estimates on the G < 20.0 sample with only 6% (10%) catastrophic errors with ∣Δ z /(1…

Abstract We demonstrate that the inference of galaxy stellar masses via spectral energy distribution (SED) fitting techniques for galaxies formed in the first billion years after the Big Bang carries fundamental uncertainties owing to the loss of star formation history (SFH) information from the very first episodes of star formation in the integrated spectra of galaxies. While this early star formation can contribute substantially to the total stellar mass of high-redshift systems, ongoing star formation at the time of detection outshines the residual light from earlier bursts, hampering the determination of accurate stellar masses. As a result, order-of-magnitude uncertainties in stellar masses can be expected. We demonstrate this potential problem via direct numerical simulation of galaxy formation in a cosmological context. In detail, we carry out two cosmological simulations with significantly different stellar feedback models, which span a significant range in SFH burstiness. We compute the mock SEDs for these model galaxies at z = 7 via calculations of 3D dust radiative…

Abstract We present ultraviolet/optical/near-infrared observations and modeling of Type II supernovae (SNe II) whose early time ( δ t < 2 days) spectra show transient, narrow emission lines from shock ionization of confined ( r < 10 15 cm) circumstellar material (CSM). The observed electron-scattering broadened line profiles (i.e., IIn-like) of H i , He i/ii , C iv , and N iii/iv/v from the CSM persist on a characteristic timescale ( t IIn ) that marks a transition to a lower-density CSM and the emergence of Doppler-broadened features from the fast-moving SN ejecta. Our sample, the largest to date, consists of 39 SNe with early time IIn-like features in addition to 35 “comparison” SNe with no evidence of early time IIn-like features, all with ultraviolet observations. The total sample includes 50 unpublished objects with a total of 474 previously unpublished spectra and 50 multiband light curves, collected primarily through the Young Supernova Experiment and Global Supernova Project collaborations. For all sample objects, we find a significant correlation between peak ultraviolet…

Abstract We present an atlas and follow-up spectroscopic observations of 87 thin stream-like structures detected with the STREAMFINDER algorithm in Gaia DR3, of which 28 are new discoveries. Here, we focus on using these streams to refine mass models of the Galaxy. Fits with a double-power-law halo with the outer power-law slope set to − β h = −3 yield an inner power-law slope of − γ h = - ( 0.97 − 0.21 + 0.17 ) , a scale radius of r 0 , h = 14.7 − 1.0 + 4.7 kpc , a halo density flattening q m , h = 0.75 ± 0.03, and a local dark matter density of ρ h ,⊙ = 0.0114 ± 0.0007 M ⊙ pc −3 . Freeing β yields β = 2.53 − 0.16 + 0.42 , but this value is heavily influenced by our chosen virial mass limit. The stellar disks are found to have a combined mass of 4.20 − 0.53 + 0.44 × 10 10 M ⊙ , with the thick disk contributing 12.4% ± 0.7% to the local stellar surface density. The scale lengths of the thin and thick disks are 2.17 − 0.08 + 0.18 and 1.62 − 0.13 + 0.72 kpc , respectively, while their scale heights are

Abstract We investigate the impact and mitigation of extragalactic foregrounds for the cosmic microwave background (CMB) lensing power spectrum analysis of Atacama Cosmology Telescope (ACT) data release 6 (DR6) data. Two independent microwave sky simulations are used to test a range of mitigation strategies. We demonstrate that finding and then subtracting point sources, finding and then subtracting models of clusters, and using a profile bias-hardened lensing estimator together reduce the fractional biases to well below statistical uncertainties, with the inferred lensing amplitude, A lens, biased by less than 0.2σ. We also show that another method where a model for the cosmic infrared background (CIB) contribution is deprojected and high-frequency data from Planck is included has similar performance. Other frequency-cleaned options do not perform as well, either incurring a large noise cost or resulting in biased recovery of the lensing spectrum. In addition to these simulation-based tests, we also present null tests on the ACT DR6 data for sensitivity of our lensing spectrum…

Abstract A Type Ia supernova (SN) at z = 1.78 was discovered in James Webb Space Telescope Near Infrared Camera imaging of the galaxy cluster PLCK G165.7+67.0 (G165; z = 0.35). The SN is situated 1.5–2 kpc from the host-galaxy nucleus and appears in three different locations as a result of gravitational lensing by G165. These data can yield a value for Hubble’s constant using time delays from this multiply imaged SN Ia that we call “SN H0pe.” Over the cluster, we identified 21 image multiplicities, confirmed five of them using the Near-Infrared Spectrograph, and constructed a new lens model that gives a total mass within 600 kpc of (2.6 ± 0.3) × 10 14 M ⊙ . The photometry uncovered a galaxy overdensity coincident with the SN host galaxy. NIRSpec confirmed six member galaxies, four of which surround the SN host galaxy with relative velocity ≲900 km s −1 and projected physical extent ≲33 kpc. This compact galaxy group is dominated by the SN host galaxy, which has a stellar mass of (5.0 ± 0.1) × 10 11 M ⊙ . The group members have specific star formation rates of 2–260 Gyr −1 derived…

Abstract We combine deep imaging data from the CEERS early release JWST survey and Hubble Space Telescope imaging from CANDELS to examine the size–mass relation of star-forming galaxies and the morphology–quenching relation at stellar masses M ⋆ ≥ 10 9.5 M ⊙ over the redshift range 0.5 < z < 5.5. In this study with a sample of 2450 galaxies, we separate star-forming and quiescent galaxies based on their star formation activity and confirm that star-forming and quiescent galaxies have different morphologies out to z = 5.5, extending the results of earlier studies out to higher redshifts. We find that star-forming and quiescent galaxies have typical Sérsic indices of n ∼ 1.3 and n ∼ 4.3, respectively. Focusing on star-forming galaxies, we find that the slope of the size–mass relation is nearly constant with redshift, as was found previously, but shows a modest increase at z ∼ 4.2. The intercept in the size–mass relation declines out to z = 5.5 at rates that are similar to what earlier studies found. The intrinsic scatter in the size–mass relation is relatively constant out to z = 5.5.

Abstract Young solar-type stars frequently produce superflares, serving as a unique window into the young Sun-Earth environments. Large solar flares are closely linked to coronal mass ejections (CMEs) associated with filament/prominence eruptions, but observational evidence for stellar superflares remains scarce. Here, we present a 12-day, multiwavelength campaign observation of young solar-type star EK Draconis (G1.5V, 50–120 Myr age) utilizing the Transiting Exoplanet Survey Satellite, the Neutron star Interior Composition ExploreR, and the Seimei telescope. The star has previously exhibited blueshifted Hα absorptions as evidence for a filament eruption associated with a superflare. Our simultaneous optical and X-ray observations identified three superflares of 1.5 × 1033–1.2 × 1034 erg. We report the first discovery of two prominence eruptions on a solar-type star, observed as blueshifted Hα emissions at speeds of 690 and 430 km s−1 and masses of 1.1 × 1019 and 3.2 × 1017 g, respectively. The faster, massive event shows a candidate of post-flare X-ray dimming with the amplitude…

Abstract The spectra of high-redshift (z ≳ 6) quasars contain valuable information on the progression of the Epoch of Reionization. At redshifts z < 6, the observed Lyman-series forest shows that the intergalactic medium is nearly ionized, while at z > 7 the observed quasar damping wings indicate high neutral gas fractions. However, there remains a gap in neutral gas fraction constraints at 6 ≲ z ≲ 7 where the Lyman-series forest becomes saturated but damping wings have yet to fully emerge. In this work, we use a sample of 18 quasar spectra at redshifts 6.0 < z < 7.1 to close this gap. We apply neural networks to reconstruct the quasars’ continuum emission around the partially absorbed Lyα line to normalize their spectra, and stack these continuum-normalized spectra in three redshift bins. To increase the robustness of our results, we compare the stacks to a grid of models from two hydrodynamical simulations, ATON and CROC, and we measure the volume-averaged neutral gas fraction, x ¯ HI , while jointly fitting for the mean quasar lifetime, t Q, for each stacked spectrum. We…

Abstract We report on an observational campaign on the bright black hole (BH) X-ray binary Swift J1727.8–1613 centered around five observations by the Imaging X-ray Polarimetry Explorer. These observations track for the first time the evolution of the X-ray polarization of a BH X-ray binary across a hard to soft state transition. The 2–8 keV polarization degree decreased from ∼4% to ∼3% across the five observations, but the polarization angle remained oriented in the north–south direction throughout. Based on observations with the Australia Telescope Compact Array, we find that the intrinsic 7.25 GHz radio polarization aligns with the X-ray polarization. Assuming the radio polarization aligns with the jet direction (which can be tested in the future with higher-spatial-resolution images of the jet), our results imply that the X-ray corona is extended in the disk plane, rather than along the jet axis, for the entire hard intermediate state. This in turn implies that the long (≳10 ms) soft lags that we measure with the Neutron star Interior Composition ExploreR are dominated by…

Abstract We present the evolution of Lyα emission derived from 53 galaxies at z = 6.6–13.2, which have been identified by multiple JWST/NIRSpec spectroscopy programs of Early Release Science, General Observer, Director's Discretionary Time, and Guaranteed Time Observations. These galaxies fall on the star formation main sequence and are typical star-forming galaxies with UV magnitudes of −22.5 ≤ M UV ≤ −17.0. We find that 15 out of 53 galaxies show Lyα emission at the >3σ level, and we obtain Lyα equivalent width (EW) measurements and stringent 3σ upper limits for the 15 and 38 galaxies, respectively. Confirming that Lyα velocity offsets and line widths of our galaxies are comparable to those of low-redshift Lyα emitters, we investigate the redshift evolution of the Lyα EW. We find that Lyα EWs statistically decrease toward high redshifts on the Lyα EW versus the M UV plane for various probability distributions of the uncertainties. We then evaluate neutral hydrogen fractions x H I with the redshift evolution of the Lyα EW and the cosmic reionization simulation results on the basis…

Abstract In this paper, we describe the “Medium Bands, Mega Science” JWST Cycle 2 survey (JWST-GO-4111) and demonstrate the power of these data to reveal both the spatially integrated and spatially resolved properties of galaxies from the local Universe to the era of cosmic dawn. Executed in 2023 November, MegaScience obtained ∼30 arcmin 2 of deep multiband NIRCam imaging centered on the z ∼ 0.3 A2744 cluster, including 11 medium-band filters and the two shortest-wavelength broadband filters, F070W and F090W. Together, MegaScience and the UNCOVER Cycle 1 treasury program provide a complete set of deep (∼28–30 mag AB ) images in all NIRCam medium- and broadband filters. This unique data set allows us to precisely constrain photometric redshifts, map stellar populations and dust attenuation for large samples of distant galaxies, and examine the connection between galaxy structures and formation histories. MegaScience also includes ∼17 arcmin 2 of NIRISS parallel imaging in two broadband and four medium-band filters from 0.9 to 4.8 μ m, expanding the footprint where robust spectral…

Abstract The era of the James Webb Space Telescope ushers stellar population models into uncharted territories, particularly at the high-redshift frontier. In a companion paper, we apply the Prospector Bayesian framework to jointly infer galaxy redshifts and stellar population properties from broadband photometry as part of the UNCOVER survey. Here we present a comprehensive error budget in spectral energy distribution (SED) modeling. Using a sample selected to have photometric redshifts higher than 9, we quantify the systematic shifts stemming from various model choices in inferred stellar mass, star formation rate (SFR), and age. These choices encompass different timescales for changes in the star formation history (SFH), nonuniversal stellar initial mass functions (IMF), and the inclusion of variable nebular abundances, gas density, and ionizing photon budget. We find that the IMF exerts the strongest influence on the inferred properties: the systematic uncertainties can be as much as 1 dex, 2–5 times larger than the formal reported uncertainties in mass and SFR, and importantly,…

Abstract We utilize deep JWST Near Infrared Camera (NIRCam) observations for the first direct constraints on the Galaxy Stellar Mass Function (GSMF) at z > 10. Our EPOCHS v1 sample includes 1120 galaxy candidates at 6.5 < z < 13.5 taken from a consistent reduction and analysis of publicly available deep JWST NIRCam data covering the Prime Extragalactic Areas for Reionization Science, CEERS, GLASS, JADES GOOD-S, NGDEEP, and SMACS0723 surveys, totaling 187 arcmin 2 . We investigate the impact of spectral energy distribution fitting methods, assumed star formation histories (SFHs), dust laws, and priors on galaxy masses and the resultant GSMF. While our fiducial GSMF agrees with the literature at z < 13.5, we find that the assumed SFH model has a large impact on the GSMF and stellar mass density (SMD), finding a 0.75 dex increase in the SMD at z = 10.5 between a flexible nonparametric and standard parametric SFH. Overall, we find a flatter SMD evolution at z ≥ 9 than some studies predict, suggesting a rapid buildup of stellar mass in the early Universe. We find no incompatibility…

Abstract The James Webb Space Telescope is unveiling a surprising lack of evolution in the number densities of ultraviolet (UV)-selected galaxies at redshift z ≳ 10. At the same time, observations and simulations are providing evidence for highly bursty star formation in high- z galaxies, resulting in significant scatter in their UV luminosities. Galaxies in low-mass dark matter halos are expected to experience most stochasticity due to their shallow potential wells. Here, we explore the impact of a mass-dependent stochasticity using a simple analytical model. We assume that scatter in the M UV – M h relation increases toward lower halo masses, following the decrease in halo escape velocity, σ UV ∼ M h − 1 / 3 , independent of redshift. Since low-mass halos are more dominant in the early universe, this model naturally predicts an increase in UV luminosity functions (LFs) at high redshifts compared to models without scatter. We make predictions for additional observables, which would be affected by stochasticity and could be used to constrain its amplitude, finding (i) galaxies are…

Abstract JWST has detected many overmassive galactic systems at z > 4, where the mass of the black hole, M •, is 10–100 times larger than expected from local relations, given the host’s stellar mass, M ⋆. This paper presents a model to describe these overmassive systems in the high-z Universe. We suggest that the black hole mass is the main driver of high-z star formation quenching. Supermassive black holes globally impact their high-z galaxies because their hosts are physically small, and the black holes have duty cycles close to unity at z > 4. In this regime, we assume that black hole mass growth is regulated by the quasar’s output, while stellar mass growth is quenched by it and uncorrelated to the global properties of the host halo. We find that the ratio M •/M ⋆ controls the average star formation efficiency: if M •/M ⋆ > 8 × 1018(nΛ/ f Edd)[(Ω b M h )/(Ω m M ⋆) − 1], then the galaxy is unable to form stars efficiently. Once this ratio exceeds the threshold, a runaway process brings the originally overmassive system toward the local M •–M ⋆ relation. Furthermore, the M •–M ⋆…

Abstract Using 20 long-term 3D core-collapse supernova simulations, we find that lower compactness progenitors that explode quasi-spherically due to the short delay to explosion experience smaller neutron star recoil kicks in the ∼100−200 km s−1 range, while higher compactness progenitors that explode later and more aspherically leave neutron stars with kicks in the ∼300−1000 km s−1 range. In addition, we find that these two classes are correlated with the gravitational mass of the neutron star. This correlation suggests that the survival of binary neutron star systems may in part be due to their lower kick speeds. We also find a correlation between the kick and both the mass dipole of the ejecta and the explosion energy. Furthermore, one channel of black hole birth leaves masses of ∼10 M ⊙, is not accompanied by a neutrino-driven explosion, and experiences small kicks. A second channel is through a vigorous explosion that leaves behind a black hole with a mass of ∼3.0 M ⊙ kicked to high speeds. We find that the induced spins of nascent neutron stars range from seconds to ∼10 ms,…

Abstract We present JWST NIRSpec prism spectroscopy of lensed galaxies at z ≳ 9 found behind the massive galaxy cluster Abell 2744 in the UNCOVER Cycle 1 Treasury Program. We confirm the redshift via emission lines and/or the Ly α break for 10 galaxies at z = 8.50–13.08 down to M V = −17.3. We achieve a 100% confirmation rate for z > 9 candidates reported in H. Atek et al. Using six sources with multiple line detections, we find that offsets in redshift estimates between the lines and the Ly α break alone can be ±0.2, raising caution in designing future follow-up spectroscopy for the break-only sources with the Atacama Large Millimeter/submillimeter Array. With spec- z -confirmed sources in UNCOVER and the literature, we derive lower limits on the rest-frame ultraviolet (UV) luminosity function (LF) at z ≃ 9–12 and find that these lower limits agree with recent photometric measurements. We identify at least two unambiguous and several possible active galactic nucleus (AGN) systems based on X-ray, broad H β , high ionization lines, and excess in the UV LF. This requires the AGN LFs…

Abstract We present a new sample of 158 galaxies at redshift z > 7.5 selected from deep James Webb Space Telescope (JWST) NIRCam imaging of five widely separated sight lines in the CANUCS survey. Two-thirds of the pointings and 80% of the galaxies are covered by 12–14 NIRCam filters, including seven to nine medium bands, providing accurate photometric redshifts and robustness against low-redshift interlopers. A sample of 28 galaxies at z > 7.5 with spectroscopic redshifts shows a low systematic offset and scatter in the difference between photometric and spectroscopic redshifts. We derive the galaxy UV luminosity function at redshifts 8–12, finding a slightly higher normalization than previously seen with the Hubble Space Telescope at redshifts 8–10. We observe a steeper decline in the galaxy space density from z = 8 to 12 than found by most JWST Cycle 1 studies. In particular, we find only eight galaxies at z > 10 and none at z > 12.5, with no z > 10 galaxies brighter than F277W AB = 28 or M UV = −20 in our unmasked, delensed survey area of 53.4 arcmin2. We attribute the lack of…

Abstract We present griz photometric light curves for the full 5 yr of the Dark Energy Survey Supernova (DES-SN) program, obtained with both forced point-spread function photometry on difference images ( DiffImg ) performed during survey operations, and scene modelling photometry (SMP) on search images processed after the survey. This release contains 31,636 DiffImg and 19,706 high-quality SMP light curves, the latter of which contain 1635 photometrically classified SNe that pass cosmology quality cuts. This sample spans the largest redshift ( z ) range ever covered by a single SN survey (0.1 < z < 1.13) and is the largest single sample from a single instrument of SNe ever used for cosmological constraints. We describe in detail the improvements made to obtain the final DES-SN photometry and provide a comparison to what was used in the 3 yr DES-SN spectroscopically confirmed Type Ia SN sample. We also include a comparative analysis of the performance of the SMP photometry with respect to the real-time DiffImg forced photometry and find that SMP photometry is more precise, more…

Abstract Low-luminosity active galactic nuclei (AGNs) with low-mass black holes (BHs) in the early universe are fundamental to understanding the BH growth and their coevolution with the host galaxies. Utilizing JWST NIRCam Wide Field Slitless Spectroscopy, we perform a systematic search for broad-line H α emitters (BHAEs) at z ≈ 4–5 in 25 fields of the A SPectroscopic survey of biased halos In the Reionization Era (ASPIRE) project, covering a total area of 275 arcmin 2 . We identify 16 BHAEs with FWHM of the broad components spanning from ∼1000 to 3000 km s −1 . Assuming that the broad line widths arise as a result of Doppler broadening around BHs, the implied BH masses range from 10 7 to 10 8 M ⊙ , with broad H α -converted bolometric luminosities of 10 44.5 –10 45.5 erg s −1 and Eddington ratios of 0.07–0.47. The spatially extended structure of the F200W stacked image may trace the stellar light from the host galaxies. The H α luminosity function indicates an increasing AGN fraction toward the higher H α luminosities. We find possible evidence for clustering of BHAEs: two sources…

Abstract We report the discovery of an extreme galaxy overdensity at z = 5.4 in the GOODS-S field using James Webb Space Telescope (JWST)/NIRCam imaging from JADES and JEMS alongside JWST/NIRCam wide-field slitless spectroscopy from FRESCO. We identified potential members of the overdensity using Hubble Space Telescope+JWST photometry spanning λ = 0.4–5.0 μ m. These data provide accurate and well-constrained photometric redshifts down to m ≈ 29–30 mag. We subsequently confirmed N = 81 galaxies at 5.2 < z < 5.5 using JWST slitless spectroscopy over λ = 3.9–5.0 μ m through a targeted line search for H α around the best-fit photometric redshift. We verified that N = 42 of these galaxies reside in the field, while N = 39 galaxies reside in a density around ∼10 times that of a random volume. Stellar populations for these galaxies were inferred from the photometry and used to construct the star-forming main sequence, where protocluster members appeared more massive and exhibited earlier star formation (and thus older stellar populations) when compared to their field galaxy counterparts.…

Abstract Deep surveys with the James Webb Space Telescope (JWST) have revealed an emergent population of moderate-luminosity, broad-line active galactic nuclei (AGNs) at 4 ≲ z ≲ 13 powered by accretion onto early massive black holes. The high number densities reported, together with the large Lyman-continuum (LyC) production efficiency and leakiness into the intergalactic medium that are typical of UV-selected AGNs, lead us to reassess a scenario where AGNs are the sole drivers of the cosmic hydrogen/helium reionization process. Our approach is based on the assumptions, grounded in recent observations, that (a) the fraction of broad-line AGNs among galaxies is around 10%–15%; (b) the mean escape fraction of hydrogen LyC radiation is high, at ≳80%, in AGN hosts and is negligible otherwise; and (c) internal absorption at 4 ryd or a steep ionizing EUV spectrum delay full reionization of He ii until z ≃ 2.8–3.0, in agreement with observations of the He ii Lyα forest. In our fiducial models, (1) hydrogen reionization is 99% completed by redshift z ≃ 5.3–5.5 and reaches its midpoint at z…

Abstract We have used public JWST/NIRSpec and JWST/NIRCam observations from the CEERS and JADES surveys in order to analyze the star-forming main sequence (SFMS) over the redshift range 1.4 ≤ z < 7. We calculate the star formation rates (SFRs) of the galaxy sample using three approaches: Balmer line luminosity, spectral energy distribution (SED) fitting, and UV luminosity. We find a larger degree of scatter about the SFMS using the Balmer-based SFRs compared to the UV-based SFRs. Because these SFR indicators are sensitive to star formation on different timescales, the difference in scatter may be evidence of bursty star formation histories in the early Universe. We additionally compare the Hα-to-UV luminosity ratio (L(Hα)/ν L ν,1600) for individual galaxies in the sample and find that 29%–52% of the ratios across the sample are poorly described by predictions from a smooth star formation history. Measuring the burstiness of star formation in the early Universe has multiple significant implications, such as deriving accurate physical parameters from SED fitting, explaining the…

Abstract We apply the cross-correlation technique to infer the Hubble constant (H 0) of the Universe using gravitational-wave (GW) sources without electromagnetic counterparts (dark sirens) from the third GW Transient Catalog (GWTC-3) and the photometric galaxy surveys 2MPZ and WISE-SuperCOSMOS, and combine these with the bright siren measurement of H 0 from GW170817. The posterior on H 0 with only dark sirens is uninformative due to the small number of well-localized GW sources. Using the eight well-localized dark sirens and the binary neutron star GW170817 with electromagnetic counterpart, we obtain a value of the Hubble constant H 0 = 75.4 − 6 + 11 km s−1 Mpc−1 (median and 68.3% equal-tailed interval) after marginalizing over the matter density and the GW bias parameters. This measurement is mostly driven by the bright siren measurement, and any constraint from dark sirens is not statistically significant. In the future, with more well-localized GW events, the constraints on expansion history will improve.

Abstract The streaming instability (SI) is a leading candidate for planetesimal formation, which can concentrate solids through two-way aerodynamic interactions with the gas. The resulting concentrations can become sufficiently dense to collapse under particle self-gravity, forming planetesimals. Previous studies have carried out large parameter surveys to establish the critical particle to gas surface density ratio (Z), above which SI-induced concentration triggers planetesimal formation. The threshold Z depends on the dimensionless stopping time (τ s , a proxy for dust size). However, these studies neglected both particle self-gravity and external turbulence. Here, we perform 3D stratified shearing box simulations with both particle self-gravity and turbulent forcing, which we characterize via a turbulent diffusion parameter, α D. We find that forced turbulence, at amplitudes plausibly present in some protoplanetary disks, can increase the threshold Z by up to an order of magnitude. For example, for τ s = 0.01, planetesimal formation occurs when Z ≳ 0.06, ≳0.1, and ≳0.2 at α D =…

Abstract HDF850.1 is the brightest submillimeter galaxy (SMG) in the Hubble Deep Field. It is known as a heavily dust-obscured star-forming galaxy embedded in an overdense environment at z = 5.18. With nine-band NIRCam images at 0.8–5.0 μ m obtained through the JWST Advanced Deep Extragalactic Survey, we detect and resolve the rest-frame UV–optical counterpart of HDF850.1, which splits into two components because of heavy dust obscuration in the center. The southern component leaks UV and H α photons, bringing the galaxy ∼100 times above the empirical relation between infrared excess and UV continuum slope (IRX– β UV ). The northern component is higher in dust attenuation and thus fainter in UV and H α surface brightness. We construct a spatially resolved dust-attenuation map from the NIRCam images, well matched with the dust continuum emission obtained through millimeter interferometry. The whole system hosts a stellar mass of 10 10.8±0.1 M ⊙ and star formation rate (SFR) of 10 2.8±0.2 M ⊙ yr −1 , placing the galaxy at the massive end of the star-forming main sequence at this…

Abstract The milestone discovery of GW170817-GRB 170817A-AT 2017gfo has shown that gravitational waves (GWs) could be produced during the merger of a neutron star–neutron star/black hole and that in electromagnetic (EM) waves, a gamma-ray burst (GRB) and a kilonova (KN) are generated in sequence after the merger. Observationally, however, EM properties before the merger phase are still unclear. Here we report a peculiar precursor in a KN-associated long-duration GRB 211211A, providing evidence of the EM before the merger. This precursor lasts ∼0.2 s, and the waiting time between the precursor and the main burst is ∼1 s, comparable to that between GW170817 and GRB 170817A. The spectrum of the precursor could be well fit with a nonthermal cutoff power-law model instead of a blackbody. In particular, a ∼22 Hz quasiperiodic oscillation candidate (∼3σ) is detected in the precursor. These temporal and spectral properties indicate that this precursor is probably produced by a catastrophic flare accompanied with magnetoelastic or crustal oscillations of a magnetar in a binary compact…

Abstract We present the results of a systematic study of the rest-frame optical morphology of quiescent galaxies at z ≥ 3 using the Near-Infrared Camera (NIRCam) on board the James Webb Space Telescope (JWST). Based on a sample selected by UVJ color or NUVUVJ color, we focus on 26 quiescent galaxies with 9.8 < log ( M ⋆ / M ⊙ ) < 11.4 at 2.8 < z phot < 4.6 with publicly available JWST data. Their sizes are constrained by fitting the Sérsic profile to all available NIRCam images. We see a negative correlation between the observed wavelength and the size and derive their size at the rest frame 0.5 μm using size measurements in multiple bands. Our quiescent galaxies show a significant correlation between the rest-frame 0.5 μm size and the stellar mass at z ≥ 3. The analytical fit for them at log ( M ⋆ / M ⊙ ) > 10.3 implies that our size–stellar mass relations are below those at lower redshifts, with the amplitude of ∼0.6 kpc at M ⋆ = 5 × 1010 M ⊙. This value agrees with the extrapolation of the size evolution of quiescent galaxies at z < 3 in the literature, implying that the size of…

Abstract Galactic compact binaries with orbital periods shorter than a few hours emit detectable gravitational waves (GWs) at low frequencies. Their GW signals can be detected with the future Laser Interferometer Space Antenna (LISA). Crucially, they may be useful in the early months of the mission operation in helping to validate LISA's performance in comparison to prelaunch expectations. We present an updated list of 55 candidate LISA-detectable binaries with measured properties, for which we derive distances based on Gaia Data Release 3 astrometry. Based on the known properties from electromagnetic observations, we predict the LISA detectability after 1, 3, 6, and 48 months using Bayesian analysis methods. We distinguish between verification and detectable binaries as being detectable after 3 and 48 months, respectively. We find 18 verification binaries and 22 detectable sources, which triples the number of known LISA binaries over the last few years. These include detached double white dwarfs, AM CVn binaries, one ultracompact X-ray binary, and two hot subdwarf binaries. We find…

Abstract The James Webb Space Telescope is revolutionizing our view of the Universe through unprecedented sensitivity and resolution in the infrared, with some of the largest gains realized at its longest wavelengths. We present the Systematic Mid-infrared Instrument (MIRI) Legacy Extragalactic Survey (SMILES), an eight-band MIRI survey with Near-Infrared Spectrograph spectroscopic follow-up in the GOODS-S/HUDF region. SMILES takes full advantage of MIRI’s continuous coverage from 5.6 to 25.5 μm over an ∼34 arcmin2 area to greatly expand our understanding of the obscured Universe up to cosmic noon and beyond. This work, together with a companion paper by G. Rieke et al., covers the SMILES science drivers and technical design, early results with SMILES, data reduction, photometric catalog creation, and the first data release. As part of the discussion on early results, we additionally present a high-level science demonstration on how MIRI’s wavelength coverage and resolution will advance our understanding of cosmic dust using the full range of polycyclic aromatic hydrocarbon emission…

Abstract We present a detailed investigation of photometric, spectroscopic, and polarimetric observations of the Type II SN 2023ixf. Earlier studies have provided compelling evidence for a delayed shock breakout from a confined dense circumstellar matter (CSM) enveloping the progenitor star. The temporal evolution of polarization in the SN 2023ixf phase revealed three distinct peaks in polarization evolution at 1.4 days, 6.4 days, and 79.2 days, indicating an asymmetric dense CSM, an aspherical shock front and clumpiness in the low-density extended CSM, and an aspherical inner ejecta/He-core. SN 2023ixf displayed two dominant axes, one along the CSM-outer ejecta and the other along the inner ejecta/He-core, showcasing the independent origin of asymmetry in the early and late evolution. The argument for an aspherical shock front is further strengthened by the presence of a high-velocity broad absorption feature in the blue wing of the Balmer features in addition to the P-Cygni absorption post-16 days. Hydrodynamical light-curve modeling indicated a progenitor mass of 10 M ⊙ with a…

Abstract Leveraging a high-resolution 3D dust map of the solar neighborhood from Edenhofer et al., we derive a new 3D model for the dust-traced surface of the Local Bubble, the supernova-driven cavity surrounding the Sun. We find that the surface of the Local Bubble is highly irregular in shape, with its peak extinction surface falling at an average distance of 170 pc from the Sun (spanning 70–600+ pc) with a typical thickness of 35 pc and a total dust-traced mass of (6.0 ± 0.7) × 10 5 M ⊙ . The Local Bubble displays an extension in the Galactic northern hemisphere that is morphologically consistent with representing a “local chimney.” We argue this chimney was likely created by the “bursting” of this supernova-driven superbubble, leading to the funneling of interstellar medium (ISM) ejecta into the lower Galactic halo. We find that many well-known dust features and molecular clouds fall on the surface of the Local Bubble and that several tunnels to other adjacent cavities in the ISM may be present. Our new, parsec-resolution view of the Local Bubble may be used to inform future…

Abstract We present gas-phase elemental abundance ratios of thirteen local extremely metal-poor galaxies (EMPGs), including our new Keck/LRIS spectroscopy determinations together with 33 James Webb Space Telescope z ∼ 4–10 star-forming galaxies in the literature, and compare chemical evolution models. We develop chemical evolution models with the yields of core-collapse supernovae (CCSNe), Type Ia SNe, hypernovae (HNe), and pair-instability supernovae (PISNe), and compare the EMPGs and high- z galaxies in conjunction with dust depletion contributions. We find that high Fe/O values of EMPGs can (cannot) be explained by PISN metal enrichments (CCSN/HN enrichments even with the mixing-and-fallback mechanism enhancing iron abundance), while the observed Ar/O and S/O values are much smaller than the predictions of the PISN models. The abundance ratios of EMPGs can be explained by the combination of Type Ia SNe and CCSNe/HNe whose inner layers of argon and sulfur mostly fallback, which are comparable to the Sculptor stellar chemical abundance distribution, suggesting that early chemical…

Abstract We expect luminous ( M 1450 ≲ −26.5) high-redshift quasars to trace the highest-density peaks in the early Universe. Here, we present observations of four z ≳ 6 quasar fields using JWST/NIRCam in the imaging and wide-field slitless spectroscopy mode and report a wide range in the number of detected [O iii ]-emitting galaxies in the quasars’ environments, ranging between a density enhancement of δ ≈ 65 within a 2 cMpc radius—one of the largest protoclusters during the Epoch of Reionization discovered to date—to a density contrast consistent with zero, indicating the presence of a UV-luminous quasar in a region comparable to the average density of the Universe. By measuring the two-point cross-correlation function of quasars and their surrounding galaxies, as well as the galaxy autocorrelation function, we infer a correlation length of quasars at 〈 z 〉 = 6.25 of r 0 QQ = 22.0 − 2.9 + 3.0 cMpc h − 1 , while we obtain a correlation length of the [O iii ]-emitting galaxies of r 0 GG = 4.1 ± 0.3 cMpc h − 1 . By comparing the correlation functions to dark-matter-only simulations…

Abstract Using Keck Planet Imager and Characterizer high-resolution ( R ∼ 35,000) spectroscopy from 2.29 to 2.49 μ m, we present uniform atmospheric retrievals for eight young substellar companions with masses of ∼10–30 M Jup , orbital separations spanning ∼50–360 au, and T eff between ∼1500 and 2600 K. We find that all companions have solar C/O ratios and metallicities to within the 1 σ –2 σ level, with the measurements clustered around solar composition. Stars in the same stellar associations as our systems have near-solar abundances, so these results indicate that this population of companions is consistent with formation via direct gravitational collapse. Alternatively, core accretion outside the CO snowline would be compatible with our measurements, though the high mass ratios of most systems would require rapid core assembly and gas accretion in massive disks. On a population level, our findings can be contrasted with abundance measurements for directly imaged planets with m < 10 M Jup , which show tentative atmospheric metal enrichment compared to their host stars. In…

Abstract We present tomographic measurements of structure growth using cross-correlations of Atacama Cosmology Telescope (ACT) DR6 and Planck cosmic microwave background (CMB) lensing maps with the unWISE Blue and Green galaxy samples, which span the redshift ranges 0.2 ≲ z ≲ 1.1 and 0.3 ≲ z ≲ 1.8, respectively. We improve on prior unWISE cross-correlations not just by making use of the new, high-precision ACT DR6 lensing maps, but also by including additional spectroscopic data for redshift calibration and by analyzing our measurements with a more flexible theoretical model. We determine the amplitude of matter fluctuations at low redshifts (z ≃ 0.2–1.6), finding S 8 ≡ σ 8 ( Ω m / 0.3 ) 0.5 = 0.813 ± 0.021 using the ACT cross-correlation alone and S 8 = 0.810 ± 0.015 with a combination of Planck and ACT cross-correlations; these measurements are fully consistent with the predictions from primary CMB measurements assuming standard structure growth. The addition of baryon acoustic oscillation data breaks the degeneracy between σ 8 and Ω m , allowing us to measure σ 8 = 0.813 ± 0.020…

Abstract We present an analysis of JWST Ly α spectroscopy of z ≳ 6.5 galaxies, using observations in the public archive covering galaxies in four independent fields: Great Observatories Origins Deep Survey (GOODS)-N, GOODS-S, A2744, and the Extended Groth Strip (EGS). We measure the Ly α emission line properties for a sample of 210 z ≃ 6.5–13 galaxies, with redshifts confirmed independently of Ly α in all cases. We present three new detections of Ly α emission in JWST spectra, including a large equivalent width (EW; =143 Å) Ly α emitter (LAE) with strong C iv emission (EW = 21 Å) at z = 7.1 in GOODS-N. We measure the redshift-dependent Ly α EW distribution across our sample. We find that strong Ly α emission (EW > 25 Å) becomes increasingly rare at earlier epochs, suggesting that the transmission of Ly α photons decreases by 4× between z ≃ 5 and z ≃ 9. We describe potential implications for the intergalactic medium neutral fraction. There is significant field-to-field variance in the LAE fraction. In contrast to the three other fields, the EGS shows no evidence for reduced…

Abstract Massive quiescent galaxies in the young Universe are expected to be quenched rapidly, but it is unclear whether they all experience starbursts before quenching and what physical mechanism drives rapid quenching. We study 14 massive quiescent galaxies ( log ( M ⋆ / M ⊙ ) > 10 ) at z ∼ 2 selected from a representative sample of the Blue Jay survey. We reconstruct their star formation histories (SFHs) by fitting spectral energy distribution models to the JWST/NIRSpec R ∼ 1000 spectra. We find that massive quiescent galaxies can be split into three categories with roughly equal numbers of galaxies according to their SFHs: (1) relatively old galaxies quenched at early epochs; (2) galaxies that are rapidly and recently quenched after a flat or bursty formation history (depending on the assumed prior); and (3) galaxies that are rapidly and recently quenched after a major starburst. Most recently quenched galaxies show neutral gas outflows, probed by blueshifted Na i D absorption, and ionized gas emission, with line ratios consistent with active galactic nucleus (AGN) diagnostics.…

Abstract We present deep JWST NIRSpec observations in the sight line of MACS J1149.5+2223, a massive cluster of galaxies at z = 0.54. We report the spectroscopic redshift of 28 sources at 3 < z < 9.1, including nine sources with the detection of the O III λ 4363 auroral line. Combining these with 16 O III λ 4363 -detected sources from publicly available JWST data, our sample consists of 25 galaxies with robust gas-phase metallicity measurements via the direct method. We observe a positive correlation between stellar mass and metallicity, with an ∼0.5 dex offset down below the local relation. Interestingly, we find a larger-than-expected scatter of ∼0.3 dex around the relation, which cannot be explained by redshift evolution among our sample or other third parameters. The scatter increases at higher redshift, and we tentatively attribute this to the enrichment process having higher stochasticity, due to shallower potential wells, more intense feedback processes, and a higher galaxy merger rate. Despite reaching a considerably low-mass regime ( log M * / M ⊙ ∼ 7.3 ), our samples have…

Abstract We follow our first paper with an analysis of the ensemble of the extensive preexplosion ground- and space-based infrared observations of the red supergiant (RSG) progenitor candidate for the nearby core-collapse supernova SN 2023ixf in Messier 101, together with optical data prior to the explosion obtained with the Hubble Space Telescope (HST). We have confirmed the association of the progenitor candidate with the supernova (SN), as well as constrained the metallicity at the SN site, based on SN observations with instruments at Gemini-North. The internal host extinction to the SN has also been confirmed from a high-resolution Keck spectrum. We fit the observed spectral energy distribution (SED) for the star, accounting for its intrinsic variability, with dust radiative-transfer modeling, which assumes a silicate-rich dust shell ahead of the underlying stellar photosphere. The star is heavily dust obscured, likely the dustiest progenitor candidate yet encountered. We found median estimates of the star’s effective temperature and luminosity of 2770 K and 9.0 × 10 4 L ⊙ ,…

Abstract Investigating Protostellar Accretion is a Cycle 1 JWST program using the NIRSpec+MIRI integral field units to obtain 2.9–28 μm spectral cubes of five young protostars with luminosities of 0.2–10,000 L ⊙ in their primary accretion phase. This paper introduces the NIRSpec 2.9–5.3 μm data of the inner 840–9000 au with spatial resolutions from 28 to 300 au. The spectra show rising continuum emission; deep ice absorption; emission from H2, H i, and [Fe ii]; and the CO fundamental series in emission and absorption. Maps of the continuum emission show scattered light cavities for all five protostars. In the cavities, collimated jets are detected in [Fe ii] for the four <320 L ⊙ protostars, two of which are additionally traced in Brα. Knots of [Fe ii] emission are detected toward the most luminous protostar, and knots of [Fe ii] emission with dynamical times of <30 yr are found in the jets of the others. While only one jet is traced in H2, knots of H2 and CO are detected in the jets of four protostars. H2 is seen extending through the cavities, showing that they are filled by warm…

Abstract We analyze a sample of 3300 galaxies between redshifts z ≃ 3.5 and z ≃ 8.5 selected from James Webb Space Telescope (JWST) images in the Hubble Ultra Deep Field and UKIDSS Ultra Deep Survey field, including objects with stellar masses as low as ≃10 8 M ⊙ up to z ≃ 8. The depth and wavelength coverage of the JWST data allows us, for the first time, to derive robust stellar masses for such high- z , low stellar mass galaxies on an individual basis. We compute the galaxy stellar mass function, after complementing our sample with ancillary data from CANDELS to constrain the GMSF at high stellar masses ( M > M * ). Our results show a steepening of the low stellar mass end slope ( α ) with redshift, with α = −1.61 ± 0.05 at z ≃ 4 and α = −1.98 ± 0.14 at z ≃ 7. We also observe an evolution of the normalization ϕ * from z ≃ 7 to z ≃ 4, with ϕ z ≃ 4 * / ϕ z ≃ 7 * = 130 − 50 + 210 . Our study incorporates a novel method for the estimation of the Eddington bias, which takes into account its possible dependence both on stellar mass and redshift, while allowing for skewness in the error…

Abstract We have performed numerical calculations of a binary interacting with a gas disk, using 11 different numerical methods and a standard binary−disk setup. The goal of this study is to determine whether all codes agree on a numerically converged solution and to determine the necessary resolution for convergence and the number of binary orbits that must be computed to reach an agreed-upon relaxed state of the binary−disk system. We find that all codes can agree on a converged solution (depending on the diagnostic being measured). The zone spacing required for most codes to reach a converged measurement of the torques applied to the binary by the disk is roughly 1% of the binary separation in the vicinity of the binary components. For our disk model to reach a relaxed state, codes must be run for at least 200 binary orbits, corresponding to about a viscous time for our parameters, 0.2( a 2 Ω B / ν ) binary orbits, where ν is the kinematic viscosity. The largest discrepancies between codes resulted from the dimensionality of the setup (3D vs. 2D disks). We find good agreement in…

Abstract The James Webb Space Telescope (JWST) has uncovered a ubiquitous population of dust-obscured compact sources at z ≳ 4. Many of these objects exhibit signs of active galactic nucleus (AGN) activity, making their study crucial for understanding the formation of supermassive black holes (SMBHs) and their growth with host galaxies. In this work, we examine low and medium-resolution JWST/NIRSpec spectra from the JADES GTO public data release in the GOODS-N field of a red, luminous (M B ∼ −22.2 mag) and compact (<500 pc) source at z = 4.13. The rest-optical (λ rest > 4000 Å) continuum of this source is strongly dominated by a massive (log10[M */M ⊙] ∼ 10.6), quenched (log10[sSFR/yr−1] < −11) galaxy, as indicated by the clear presence of a Balmer break and stellar absorption lines. Star formation history modeling reveals a starburst episode followed by rapid quenching about 200 Myr ago. The spectrum shows extremely broad (FWHM ∼2500 km s−1) Hα emission and elevated optical line ratios, indicating an actively accreting SMBH. Moreover, our work has potentially revealed clear AGN…

Abstract The idea of composite dark energy (DE) is quite natural since on general grounds we expect that the vacuum energy density (associated with the cosmological term Λ) may appear in combination with other effective forms of DE, denoted X . Here we deal with model w XCDM, a simplified version of the old ΛXCDM model, and exploit the possibility that X behaves as “phantom matter” (PM), which appears in stringy versions of the running vacuum model (RVM). Unlike phantom DE, the PM fluid satisfies the strong energy condition like usual matter, hence bringing to bear positive pressure at the expense of negative energy. Bubbles of PM may appear in the manner of a transitory “phantom vacuum” tunneled into the late Universe before it heads toward a new de Sitter era, thereby offering a crop field for the growing of structures earlier than expected. Using Type Ia supernovae, cosmic chronometers, transversal baryon acoustic oscillations (BAO 2D), large-scale structure data, and the full cosmic microwave background likelihood from Planck 2018, we find that the H 0 and growth tensions…

Abstract In 2021, a catalog of 536 fast radio bursts (FRBs) detected with the Canadian Hydrogen Intensity Mapping Experiment (CHIME) radio telescope was released by the CHIME/FRB Collaboration. This large collection of bursts, observed with a single instrument and uniform selection effects, has advanced our understanding of the FRB population. Here we update the results for 140 of these FRBs for which channelized raw voltage (“baseband”) data are available. With the voltages measured by the telescope’s antennas, it is possible to maximize the telescope sensitivity in any direction within the primary beam, an operation called “beamforming.” This allows us to increase the signal-to-noise ratios of the bursts and to localize them to subarcminute precision. The improved localizations are also used to correct the beam response of the instrument and to measure fluxes and fluences with an ∼10% uncertainty. Additionally, the time resolution is increased by 3 orders of magnitude relative to that in the first CHIME/FRB catalog, and, applying coherent dedispersion, burst morphologies can be…

Abstract Substantial populations of massive quiescent galaxies at z ≥ 3 challenge our understanding of rapid galaxy growth and quenching over short timescales. In order to piece together this evolutionary puzzle, more statistical samples of these objects are required. Established techniques for identifying massive quiescent galaxies are increasingly inefficient and unconstrained at z > 3. As a result, studies report that as much as 70% of quiescent galaxies at z > 3 may be missed from existing surveys. In this work, we propose a new empirical color selection technique designed to select massive quiescent galaxies at 3 ≲ z ≲ 6 using JWST NIRCam imaging data. We use empirically constrained galaxy spectral energy distribution (SED) templates to define a region in the F277W − F444W versus F150W − F277W color plane that captures quiescent galaxies at z > 3. We apply these color selection criteria to the Cosmic Evolution Early Release Science (CEERS) Survey and use SED fitting on sources in the region to identify 44 candidate z ≳ 3 quiescent galaxies. Over half of these sources are newly…

Abstract “Changing-look” active galactic nuclei (CL-AGNs) challenge our basic ideas about the physics of accretion flows and circumnuclear gas around supermassive black holes. Using first-year Sloan Digital Sky Survey V (SDSS-V) repeated spectroscopy of nearly 29,000 previously known active galactic nuclei (AGNs), combined with dedicated follow-up spectroscopy, and publicly available optical light curves, we have identified 116 CL-AGNs where (at least) one broad emission line has essentially (dis-)appeared, as well as 88 other extremely variable systems. Our CL-AGN sample, with 107 newly identified cases, is the largest reported to date, and includes ∼0.4% of the AGNs reobserved in first-year SDSS-V operations. Among our CL-AGNs, 67% exhibit dimming while 33% exhibit brightening. Our sample probes extreme AGN spectral variability on months to decades timescales, including some cases of recurring transitions on surprisingly short timescales (≲2 months in the rest frame). We find that CL events are preferentially found in lower-Eddington-ratio ( f Edd ) systems: Our CL-AGNs have a f…

Abstract A large energy-dependent X-ray polarization degree is detected by the Imaging X-ray Polarimetry Explorer (IXPE) in the high-soft emission state of the black hole X-ray binary 4U 1630–47. The highly significant detection (at ≈50 σ confidence level) of an unexpectedly high polarization, rising from ∼6% at 2 keV to ∼10% at 8 keV, cannot be easily reconciled with standard models of thin accretion disks. In this work, we compare the predictions of different theoretical models with the IXPE data and conclude that the observed polarization properties are compatible with a scenario in which matter accretes onto the black hole through a thin disk covered by a partially ionized atmosphere flowing away at mildly relativistic velocities.

Abstract We report JWST/NIRSpec spectra of three distant T-type brown dwarfs identified in the Ultradeep NIRSpec and NIRCam ObserVations before the Epoch of Reionization (UNCOVER) survey of the Abell 2744 lensing field. One source was previously reported as a candidate T dwarf on the basis of NIRCam photometry, while two sources were initially identified as candidate active galactic nuclei. Low-resolution 1–5 μ m spectra confirm the presence of molecular features consistent with T dwarf atmospheres, and comparison to spectral standards infers classifications of sdT1, T6, and T8–T9. The warmest source, UNCOVER-BD-1, shows evidence of subsolar metallicity, and atmosphere model fits indicate T eff = 1300 K and [M/H] ∼ −1.0, making this one of the few spectroscopically confirmed T subdwarfs known. The coldest source, UNCOVER-BD-3, is near the T/Y dwarf boundary with T eff = 550 K, and our analysis indicates the presence of PH 3 in the 3–5 μ m region, favored over CO 2 and a possible indicator of subsolar metallicity. We estimate distances of 0.9–4.5 kpc from the Galactic midplane,…

Abstract We present Data Release 3 (DR3) of the Satellites Around Galactic Analogs (SAGA) Survey, a spectroscopic survey characterizing satellite galaxies around Milky Way (MW)-mass galaxies. The SAGA Survey DR3 includes 378 satellites identified across 101 MW-mass systems in the distance range of 25–40.75 Mpc, and an accompanying redshift catalog of background galaxies (including about 46,000 taken by SAGA) in the SAGA footprint of 84.7 deg 2 . The number of confirmed satellites per system ranges from zero to 13, in the stellar mass range of 10 6−10 M ⊙ . Based on a detailed completeness model, this sample accounts for 94% of the true satellite population down to M ⋆ = 10 7.5 M ⊙ . We find that the mass of the most massive satellite in SAGA systems is the strongest predictor of satellite abundance; one-third of the SAGA systems contain LMC-mass satellites, and they tend to have more satellites than the MW. The SAGA satellite radial distribution is less concentrated than the MW's, and the SAGA quenched fraction below 10 8.5 M ⊙ is lower than the MW's, but in both cases, the MW is…

Abstract We present the robust selection of high-redshift quiescent galaxies (QG) and poststarburst (PSB) galaxies using ultra-deep NIRCam and MIRI imaging from the JWST Advanced Deep Extragalactic Survey (JADES). At 3 < z < 6, MIRI 7.7 μ m imaging provides rest-frame J band, which is commonly used to break the degeneracy between old stellar populations and dust attenuation at lower redshifts. We identify 23 passively evolving galaxies in UVJ color space in a mass-limited (log M ⋆ / M ⊙ ≥ 8.5) sample over 8.8 arcmin 2 . An evaluation of the contribution of the 7.7 μ m shows that JADES-like NIRCam coverage (9+ photometric bands) can compensate for lacking the J band at these redshifts; however, more limited three-band selections perform better with MIRI. Our sample is characterized by rapid quenching timescales (∼100–600 Myr) with formation redshifts z f ≲ 9 and includes a potential record-holding massive QG at z phot = 5.33 − 0.17 + 0.16 and two QGs with evidence for significant residual dust content ( A V ∼ 1–2). In addition, we present a large sample of 12 log M ⋆ / M ⊙ = 8.5–9.5…

Abstract We conduct a systematic search for high-redshift galaxy overdensities at 4.9 < z spec < 8.9 in both the Great Observatories Origins Deep Survey (GOODS)-N and GOODS-S fields using James Webb Space Telescope/Near-Infrared Camera (JWST/NIRCam) imaging from the JWST Advanced Deep Extragalactic Survey and JWST Extragalactic Medium-band Survey in addition to JWST/NIRCam wide field slitless spectroscopy from the First Reionization Epoch Spectroscopic Complete Survey. High-redshift galaxy candidates are identified using Hubble Space Telescope + JWST photometry spanning λ = 0.4–5.0 μ m. We confirmed the redshifts for roughly a third of these galaxies using JWST spectroscopy over λ = 3.9–5.0 μ m through identification of either H α or OIII λ 5008 around the best-fit photometric redshift. The rest-ultraviolet magnitudes and continuum slopes of these galaxies were inferred from the photometry: the brightest and reddest objects appear in more dense environments and thus are surrounded by more galaxy neighbors than their fainter and bluer counterparts, suggesting accelerated galaxy…

Abstract By combining the James Webb Space Telescope (JWST)/NIRCam JADES and CEERS extragalactic data sets, we have uncovered a sample of 21 T and Y brown dwarf candidates at best-fit distances between 0.1 and 4.2 kpc. These sources were selected by targeting the blue 1–2.5 μ m colors and red 3–4.5 μ m colors that arise from molecular absorption in the atmospheres of T eff < 1300 K brown dwarfs. We fit these sources using multiple models of substellar atmospheres and present the resulting fluxes, sizes, effective temperatures, and other derived properties for the sample. If confirmed, these fits place the majority of the sources in the Milky Way thick disk and halo. We observe proper motions for seven of the candidate brown dwarfs, with directions in agreement with the plane of our Galaxy, providing evidence that they are not extragalactic in nature. We demonstrate how the colors of these sources differ from selected high-redshift galaxies, and explore the selection of these sources in planned large-area JWST NIRCam surveys. Deep imaging with JWST/NIRCam presents an an excellent…

Abstract We report on the spectroscopic confirmation of a massive quiescent galaxy at z spec = 4.53 in the COSMOS field. The object was first identified as a galaxy with suppressed star formation at z phot ∼ 4.65 from the COSMOS2020 catalog. The follow-up spectroscopy with Keck/MOSFIRE in the K band reveals faint [O ii ] emission and the Balmer break, indicative of evolved stellar populations. We fit the spectral energy distribution using photometry and a spectrum to infer physical properties. The obtained stellar mass is high ( M * ∼ 10 10.8 M ⊙ ) and the current star formation rate is more than 1 dex below that of main-sequence galaxies at z = 4.5. Its star formation history suggests that this galaxy experienced rapid quenching from z ∼ 5. The galaxy is among the youngest quiescent galaxies confirmed so far at z spec > 3 with z form ∼ 5.2 (200 Myr ago), which is the epoch when 50% of the total stellar mass was formed. A unique aspect of the galaxy is that it is in an extremely dense region; there are four massive star-forming galaxies at 4.4 < z phot < 4.7 located within 150…