The 10 most-cited articles in Astronomische Nachrichten, 2022

Abstract The minimum–maximum method, belonging to the precursor class of the solar activity forecasting methods, is based on a linear relationship between relative sunspot number in the minimum and maximum epochs of solar cycles. In the present analysis, we apply a modified version of this method using data not only from the minimum year, but also from a couple of years before and after the minimum. The revised 13‐month smoothed monthly total sunspot number data set from Sunspot Index and Long‐term Solar Observations/SIDC is used. Using data for solar cycle nos. 1–24 the largest correlation coefficient ( ) is obtained when correlating activity level 3 years before solar cycle minimum with the subsequent maximum ( ), independent of inclusion or exclusion of the solar cycle no. 19. For the next solar maximum of the cycle no. 25, we predict: . Our results indicate that the next solar maximum (of the cycle no. 25) will be of the similar amplitude as the previous one, or even something lower. This is in accordance with the general middle‐term lowering of the solar activity after the…

Abstract We review problems raised by Fe II emission in active galactic nuclei (AGNs) and address the question of its relationship to other broad‐line region (BLR) lines. The self‐shielding, stratified, BLR model of Gaskell, Klimek & Nazarova (Astrophysics, 2007; GKN) predicts that Fe II emission comes from twice the radius of Hβ, in agreement with widths of lines of Fe II lines being only 70% of the widths of Hβ. This disagrees with some reverberation mapping results, which have suggested that Fe II and Hβ arise at similar radii. The highest quality reverberation mapping, however, supports the predictions that Fe II comes from twice the radius of Hβ. We suggest that lower quality reverberation mapping of Fe II is biased to give too small lags. We conclude that, in agreement with the GKN model, the region emitting Fe II is the outermost part of the BLR just inside the surrounding dust. The model naturally gives the Doppler broadening required by models of Fe II emission. Optical Fe II emission implies typical reddenings of . This helps to explain the ratio of UV to optical Fe II…

Abstract Inspired by the quantum gravity prescriptions, for instance, string theory, doubly‐special relativity, and quantum loop gravity, we apply the generalized relativistic noncommutative Heisenberg algebra on the eight‐dimensional Finsler manifold, the natural generalization of the four‐dimensional Riemann manifold. The Finsler manifold is conjectured to relax the quadratic restriction on the length measure, especially in the relativistic regime. The additional curvature coupled with the Finsler manifold is assumed to mimic the quantization on the Riemann manifold. The second ingredient we suggest is the existence of a minimum measurable length, whose value is determined from the relativistic generalized uncertainty principle, and then applying in to the coordinates of the Finsler manifold. The quantum‐induced corrections to the fundamental tensor are determined under extreme conditions of a relativistic energy. Whether this proposal is adequate for a full quantization, the various limitations of the proposed theory are elaborated and discussed, especially the limitations of the…

Abstract The strong chromospheric absorption lines Ca ii H & K are tightly connected to stellar surface magnetic fields. Only for the Sun, spectral activity indices can be related to evolving magnetic features on the solar disk. The Solar Disk‐Integrated (SDI) telescope feeds the Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) of the Large Binocular Telescope (LBT) at Mt. Graham International Observatory, Arizona, U.S.A. We present high‐resolution, high‐fidelity spectra that were recorded on 184 & 82 days in 2018 & 2019 and derive the Ca ii H & K emission ratio, that is, the S‐index. In addition, we compile excess brightness and area indices based on full‐disk Ca ii K‐line‐core filtergrams of the Chromospheric Telescope (ChroTel) at Observatorio del Teide, Tenerife, Spain and full‐disk ultraviolet (UV) 1600 Å images of the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO). Thus, Sun‐as‐a‐star spectral indices are related to their counterparts derived from resolved images of the solar chromosphere. All indices display signatures of…

Abstract For a rigorous approach to reconcile principles of general relativity (GR) and quantum mechanics (QM), we suggest applying the generalized relativistic noncommutative Heisenberg algebra on spacetime coordinates and momenta of a test particle on curved Riemann geometry manifold, which in turn is extended to an eight‐dimensional manifold. The natural generalization of the four‐dimensional Riemann geometry is the Finsler geometry, in which the quadratic restriction on the length measure is relaxed. With the minimum measurable length derived from the relativistic generalized four‐dimensional uncertainty principle, the quantum‐induced corrections to the fundamental tensor could be determined in the relativistic regime. Accordingly, the affine connections could be revisited. With the quantum‐induced revisiting Riemann curvature tensor and its contractions, the Ricci curvature tensor, and then the Ricci scalar, we have been able to construct a quantum‐induced revision of the Einstein tensor, in which besides quantum‐induced corrections, additional geometric structures emerge. On…

Abstract In the General Theory of Relativity (GR) gravitational interactions are described by the scalar Ricci curvature. But there exists another class of modified gravity theories equivalent to GR, described by the torsion tensor or non‐metricity scalar. One of such theories, investigated in this paper is gravity, built from the arbitrary function of non‐metricity scalar non‐minimally coupled to the trace of stress‐energy tensor. Current work is aimed on the linear gravity, where and are free MOG parameters to be varied. As well, we assume that the fluid is bulk‐viscous with pressure and the bulk viscosity parameter . From the modified Einstein Field Equations (EFE's) we obtain the Hubble parameter analytically and constrain free parameters of the model through the MCMC sampling of 57 recent Hubble parameter observations. We found that computed Hubble rate for our model from MCMC sampling converges with the observational data at the confidence level. To examine the current accelerated expansion rate of the universe in details we use the statefinder diagnostics. Besides, to…

Abstract The latest results from our ongoing multiplicity study of (Community) TESS Objects of Interest are presented, using astro‐ and photometric data from the ESA‐Gaia mission, to detect stellar companions of these stars and characterize their properties. A total of 124 binary and 7 hierarchical triple star systems were detected among 2175 targets, whose multiplicity was investigated in the course of our survey, which are located at distances closer than about 500 pc around the Sun. The detected companions and the targets are located at the same distance and share a common proper motion, as expected for components of gravitationally bound stellar systems, as proven with their accurate Gaia EDR3 astrometry. The companions have masses in the range between about 0.09 and 2.5 and are most frequently found in the mass range between 0.15 and 0.8 . The companions exhibit projected separations to the targets between about 50 to 9700 au and their frequency is the highest and constant up to about 500 au, while it decreases for larger projected separations. In addition to mainly mid M to…

Abstract Multiple previous studies using several different probes have shown considerable evidence for the existence of cosmological‐scale anisotropy and a Hubble‐scale axis. One of the probes that show such evidence is the distribution of the directions toward which galaxies spin. The advantage of the analysis of the distribution of galaxy spin directions compared to the cosmic microwave background anisotropy is that the ratio of galaxy spin directions is a relative measurement, and therefore less sensitive to background contamination such as Milky Way obstruction. Another advantage is that many spiral galaxies have spectra, and therefore allow to analyze the location of such axis relative to Earth. This paper shows an analysis of the distribution of the spin directions of over 90K galaxies with spectra. That analysis is also compared to previous analyses using the Earth‐based Sloan Digital Sky Survey, Panoramic Survey Telescope and Rapid Response System, and Dark Energy Spectroscopic Instrument Legacy Survey, as well as space‐based data collected by Hubble Space Telescope. The…

Abstract A modification of the Einstein–Hilbert theory, the Covariant Canonical Gauge Gravity (CCGG), leads to a cosmological constant that represents the energy of the space–time continuum when deformed from its (A)dS ground state to a flat geometry. CCGG is based on the canonical transformation theory in the De Donder–Weyl (DW) Hamiltonian formulation. That framework modifies the Einstein–Hilbert Lagrangian of the free gravitational field by a quadratic Riemann–Cartan concomitant. The theory predicts a total energy‐momentum of the system of space–time and matter to vanish, in line with the conjecture of a “Zero‐Energy‐Universe” going back to Lorentz (1916) and Levi‐Civita (1917). Consequently, a flat geometry can only exist in presence of matter where the bulk vacuum energy of matter, regardless of its value, is eliminated by the vacuum energy of space–time. The observed cosmological constant Λobs is found to be merely a small correction attributable to deviations from a flat geometry and effects of complex dynamical geometry of space–time, namely torsion and possibly also vacuum…

Abstract We basis our initial analysis of the arrow of time on a relationship between the time evolution operator of quantum system and the time‐independent density operator, which describes the equilibrium state of a many‐particle system at temperature . We highlight through this analysis the identification of the imaginary temporal component of the branch‐cut complex cosmic form factor with the direction in which the time parameter flows globally, or the arrow of time. As a novelty, in this work, we calculate the number of branches in the branch‐cut universe to achieve causality involving the global time of evolution of the universe and the local time of travel of the light around each Hubble horizon. The preliminary result obtained is comparable to 60 e‐folds of contraction in the FLRW cosmic scale factor to overcome causality achieved in the bouncing model.