galaxies

First author: Azton I. Wells We incorporate new scale-intelligent models of metal-enriched star formation (\starss) with surrogate models of primordial stellar feedback (\starnet) into the astrophysics simulation code \enzo to analyze the impact of heterogeneous metal enrichment on the first galaxies. Our study includes the earliest generations of stars and the protogalaxies ($10^6 \lesssim M_v/M_\odot \lesssim 10^8$) containing them. We compare results obtained with the new methods to two common paradigms of metallicity initial conditions in simulations: ignoring the metallicity initial condition and assuming a uniform metallicity floor.

First author: George Contopoulos The most important theory of the spiral arms of galaxies is the density wave theory based on the Lin-Shu dispersion relation. However, the density waves move with the group velocity towards the inner Lindblad resonance and tend to disappear. Various mechanisms to replenish the spiral waves have been proposed. Nonlinear effects play an important role near the inner and outer Lindblad resonances and corotation. The orbits supporting the spiral arms are precessing ellipses in normal galaxies that extend up to the 4/1 resonance.

First author: Aditi Vijayan Interstellar (ISM) and circumgalactic medium (CGM) around galaxies are linked to several physical processes that drive galaxy evolution. For example, the X-ray emission from the CGM gas around ellipticals has been linked to the AGN feedback occurring in the host. Upcoming telescopes such as HUBS, with ~ 1 eV resolution, can provide us with deep insights about the hot gas properties of such galaxies thus constrain these processes.

First author: G. Pascoli The existence of the flat rotation curves of galaxies is still perplexing. The dark matter paradigm was proposed long ago to solve this conundrum; however, this proposal is still under debate. In this paper, we search for universal relationships solely involving the baryonic density that incorporate both galactic dynamics and gravitational lensing in galaxy clusters without requiring dark matter. If this type of formula exists, we show that it is possible that it can clearly indicate that dark matter is either perfectly tailored to baryonic matter or, from a more radical point of view, even perhaps useless.

First author: Yang-Ji Li We report on the identification of a new $\gamma$-ray emitting narrow-line Seyfert 1 galaxy ($\gamma$-NLS1), SDSS J095909.51+460014.3 (hereinafter J0959+4600, $z$ = 0.399), by establishing its association with a $\gamma$-ray source 4FGL 0959.6+4606, although its low-energy counterpart was suggested to be a radio galaxy 2MASX J09591976+4603515 (hereinafter J0959+4603). \emph{WISE} long-term light curves of these two sources reveal diverse infrared variability patterns. Violent infrared variations of J0959+4600 with an amplitude up to one order of magnitude has been detected, while variability is mild for the other one.

First author: Kasper E. Heintz Galaxies throughout the last 12 Gyr of cosmic time follow a single, universal fundamental plane that relates their star-formation rates (SFRs), stellar masses ($M_\star$) and chemical abundances. Deviation from these fundamental scaling relations would imply a drastic change in the processes that regulate galaxy evolution. Observations have hinted at the possibility that this relation may be broken in the very early universe. However, until recently, chemical abundances of galaxies could be only measured reliably as far back as redshift $z = 3.

First author: Lior Shamir The discrepancy between the mass of galaxies and their rotational velocity is one of the most puzzling scientific phenomena. Despite over a century of research, this phenomenon is not fully understood. Common explanations include dark matter and MOND, among other theories. Here we report on another observation that shows tension between the physics of galaxy rotation and its rotational velocity. We compare the brightness of galaxies, and find that galaxies that spin in the same direction as the Milky Way have different brightness than galaxies that spin in the opposite direction.

First author: Varenya Upadhyaya We search for a linearity in the ratio of dark matter to baryonic matter as a function of radius for galaxy clusters, motivated by a recent result by Lovas (arXiv:2206.11431), who has discovered such a linearity for a diverse suite of galaxies in the SPARC sample. For our analysis, we used a sample of 54 non-cool core clusters from the HIFLUGCS sample. We do not find any evidence for a linear trend in the aforementioned ratio as a function of radius for individual clusters.

First author: Vaishnav V. Rao The Seyfert galaxy NGC 2639 is known to exhibit three episodes of AGN jet/lobe activity. We present here the upgraded Giant Metrewave Radio Telescope (uGMRT) 735 MHz image of NGC 2639 showing a fourth episode as witnessed by the discovery of $\sim9$ kpc radio lobes misaligned with the previously known $\sim1.5$ kpc, $\sim360$ parsec, and $\sim3$ parsec jet features detected through the Karl G. Jansky Very Large Array (VLA) and the Very Long Baseline Array (VLBA), respectively.

First author: Andrew King A suggested model for quasi–periodic eruptions (QPEs) from galaxy nuclei invokes a white dwarf in an eccentric orbit about the central massive black hole. I point out that the extreme mass ratio allows the presence of strong Lindblad resonances in the accretion disc. These are important for the stability of mass transfer, and may trigger the eruptions themselves by rapidly transferring angular momentum from the accretion disc (which is likely to be eccentric itself) to the orbiting WD companion at pericentre.