arXiv subjects

Evgenii V. Rubtsov

Publications and source records attributed to Evgenii V. Rubtsov.

4 recordsLinked to original sources

arXiv2026

The Edge-on Galaxies in the DESI survey (EGIDE): sample building and photometry

We present the EGIDE (The Edge-on Galaxies in the DESI survey) project - a catalogue of 149,215 edge-on galaxy candidates created using the data of the DESI Legacy Imaging Survey DR10 images. The catalogue size is ten times bigger than its predecessor and covers more than half of the sky. It is constructed in an automatic way utilizing the full power of manual annotations from the GalaxyZoo volunteers, implemented in the Zoobot neural model, which was fine-tuned to search for edge-on galaxies specifically. To ensure the credibility of the dataset, subsequent manual supervision was done. The EGIDE catalogue provides homogeneous SExtractor photometry in $griz$ bands, total stellar mass estimation, redshift values for 98% of the sample, star formation rates and other information. All of this is publicly available at The Edge-on Galaxy Database site. The preliminary analysis focused on differences between edge-on galaxies in the so-called blue sequence and red cloud populations. These galaxies demonstrate distinct properties: the number of redder galaxies drops with increasing $a/b$ ratio faster than for the bluer galaxies; galaxy thickness varies with galaxy colour: red sequence galaxies are thicker than blue cloud galaxies; the flattening ratio $q=b/a$ increases with total stellar mass $M_{\star}$ for the high-mass end. It is an intriguing result, that the same trend of $q$ increasing is detected from both the statistical models of figures of revolution and direct observations of edge-on galaxies in EGIDE independently. The full extent of the validity of this relationship can only be determined after correctly accounting for the contributions of the bulge and the PSF.

astro-ph.GA↗

arXiv2026

MUSE Study of Two Giant Low-surface-brightness Galaxies with Compact Satellites

Giant low-surface-brightness disk galaxies (gLSBGs) are rare objects with disk radii up-to 160 kpc and dynamical masses of an order of up to 10$^{12}$ $M_{\odot}$. Their very existence challenges currently accepted theories of galaxy formation and evolution, as it is difficult to build such large, dynamically cold disks through mergers without destroying them. We present deep MUSE mosaic observations of two nearby gLSBGs with compact elliptical satellites: UGC 1382, which hosts a globally counter-rotating gaseous disk, and AGC 192040, which does not. We analyze properties of ionized gas and present spatially resolved kinematics and metallicity maps; as well as stellar population analysis for the central regions of the galaxies. The radial gradients of gas-phase metallicities are flat for both galaxies. Our estimates of the effective oxygen yield suggest 'passive' gas in the outskirts of both stellar systems that is not involved in star formation. Our observational data indicate that both galaxies experienced mergers several Gyrs ago. However, the scenarios of formation of giant disks appear to be slightly different for these two systems. For AGC 192040 we propose the gas accretion from the filament followed by the intermediate-mass ratio merger with the companion on a prograde orbit. For UGC 1382 multiple gas-rich mergers with companions on retrograde orbits are preferred by the data.

astro-ph.GA↗

arXiv2025

Stellar CoRGI in MaNGA: Stellar Counterrotating Galaxies Identified in the MaNGA Survey

Stellar counterrotating (CR) galaxies are systems hosting two large-scale stellar components rotating in opposite directions -- a main, preexisting galaxy body with an older stellar population and a younger CR stellar disk likely formed from externally accreted gas. Such systems offer a unique opportunity to study disk assembly by analyzing the stellar populations of each component. Using integral field spectroscopic data from the SDSS-IV Mapping Nearby Galaxies at Apache Point Observatory survey, we identified a sample of 120 CR disk galaxies (65 reliable and 55 probable systems) by inspecting their kinematic maps and analyzing the shape of the stellar line-of-sight velocity distribution, which was recovered nonparametrically. Of these, 74 CR galaxies have not been reported in previous studies. For one-third of our sample, we further derived the ages and metallicities of stars for both disks via a spectral decomposition technique. We show that the observed spatial bimodality -- where the CR disk either is concentrated in the central region (inner counterrotation) or dominates the outer part of the galaxy (outer counterrotation) -- is driven by differences in the stellar mass and angular momentum of the CR disk. The wide range of stellar metallicities observed in CR disks suggests that no single source of external material is solely responsible for the formation of counterrotation in all galaxies; instead, proposed mechanisms such as merger with gas-rich satellites, accretion from cosmic filaments, and exchange of gas between neighboring galaxies can dominate in individual cases.

astro-ph.GA↗

arXiv2024

A closer look at the extended edge-on low-surface brightness galaxies

To understand the origin of extended disks of low-surface brightness (LSB) galaxies, we studied in detail 4 such systems with large disks seen edge-on. Two of them are edge-on giant LSB galaxies (gLSBGs) recently identified by our team. The edge-on orientation of these systems boosts their surface brightnesses that provided an opportunity to characterize stellar populations spectroscopically and yielded the first such measurements for edge-on gLSBGs. We collected deep images of one galaxy using the 1.4-m Milanković Telescope which we combined with the archival Subaru Hyper Suprime-Cam and DESI Legacy Surveys data available for the three other systems, and measured the structural parameters of the disks. We acquired deep long-slit spectra with the Russian 6-meter telescope and the 10-m Keck II telescope and estimated stellar population properties in the high- and low-surface brightness regions as well as the gas-phase metallicity distribution. The gas metallicity gradients are shallow to flat in the range between 0 and -0.03 dex per exponential disk scale length, which is consistent with the extrapolation of the gradient -- scale length relation for smaller disk galaxies. Our estimates of stellar velocity dispersion in the LSB disks as well as the relative thickness of the disks indicate the dynamical overheating. Our observations favor mergers as the essential stage in the formation scenario for massive LSB galaxies.

astro-ph.GA↗