arXiv subjects

V. P. Reshetnikov

Publications and source records attributed to V. P. Reshetnikov.

At least 19 recordsLinked to original sources

arXiv2024

Edge-on galaxies in the HST COSMOS field: the evolution of stellar discs up to z$\sim$0.5

We present a sample of 950 edge-on spiral galaxies found with the use of an artificial neural network in the Hubble Space Telescope COSMOS field. This is currently the largest sample of distant edge-on galaxies. For all galaxies we analyzed the 2D brightness distributions in the F814W filter and measured the radial and vertical exponential scales ($h$ and $h_z$ correspondingly) of the brightness distribution. By comparing the characteristics of distant galaxies with those of nearby objects, we conclude that thin stellar discs with $h/h_z \geq 10$ at $z \approx 0.5$ should be rarer than today. Both exponential scales of the stellar disc show evidence of luminosity-dependent evolution: in faint galaxies the $h$ and $h_z$ values do not change with $z$, in bright (and massive) spiral galaxies both scales, on average, grow towards our epoch.

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arXiv2023

The possible evolution of pitch angles of spiral galaxies

The origin and maintenance of spiral structure in galaxies, the correlation between different types of spiral structure and several proposed mechanisms for their generation, and the evolution of spiral arms of galaxies with time are questions that are still controversial. In this note we study the spiral structure in a sample of distant galaxies in order to infer the evolution of spiral arm characteristics with redshift. We considered a sample of 171 face-on spiral galaxies in the Hubble Space Telescope COSMOS (The Cosmic Evolution Survey) field. The galaxies are distributed up to $z \approx 1$ with a mean value of 0.44. For all galaxies, we determined the pitch angles of the spiral arms and analysed their dependence on redshift; a total of 359 arms were measured. Analyses of our measurements combined with the literature data suggest a possible evolution of the pitch angles of spiral galaxies: by the modern epoch the spiral pattern, on average, becomes more tightly wound. This may be a consequence of the general evolution of the structure of galaxies as galaxies become more massive over time and their bulges grow. In addition, the distribution of the cotangent of pitch angle of galaxies indicates the possibility that the dominant mechanism of spiral pattern generation changes over time.

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arXiv2023

Evolution of the spiral structure of galaxies from the HST COSMOS field

We have investigated the pitch angle ($ψ$) of the spiral arms of galaxies in the Hubble Space Telescope COSMOS field. The sample consists of 102 face-on galaxies with a two-armed pattern at a mean redshift $\langle z \rangle \approx 0.5$. The typical values of $ψ$ in the spiral arms of distant galaxies are shown to be close to those for nearby spiral galaxies. Within one galaxy the scatter of $ψ$ for different arms is, on average, half the mean pitch angle. In the $z$ range from 1 to 0 we have found a tendency for $ψ$ to decrease. Our analysis of the $ψ$ distributions in galaxies at different redshifts is consistent with the assumption that in most of the galaxies at $z \leq 0.5$ the spiral arms are tidal in origin or they arose from transient recurrent instabilities in their disks.

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arXiv2021

Spectral Observations of Superthin Galaxies

We conduct spectral observations of 138 superthin galaxies (STGs) with high radial-to-vertical stellar disk scales ratio with the Dual Imaging Spectrograph (DIS) on the 3.5m telescope at the Apache Point Observatory (APO) to obtain the ionized gas rotation curves with R ~ 5000 resolution. We also performed near infrared (NIR) H and Ks photometry for 18 galaxies with the NICFPS camera on the 3.5m telescope. The spectra, the NIR photometry and published optical and NIR photometry are used for modeling that utilizes the thickness of the stellar disk and rotation curves simultaneously. The projection and dust extinction effects are taken into account. We evaluate eight models that differ by their free parameters and constraints. As a result, we estimated masses and scale lengths of the galactic dark halos. We find systematic differences between the properties of our red and blue STGs. The blue STGs have a large fraction of dynamically under-evolved galaxies whose vertical velocity dispersion is low in both gas and stellar disks. The dark halo-to-disk scale ratio is shorter in the red STGs than in the blue ones, but in a majority of all STGs this ratio is under 2. The optical color $(r-i)$ of the superthin galaxies correlates with their rotation curve maximum, vertical velocity dispersion in stellar disks, and mass of the dark halo. We conclude that there is a threshold central surface density of 50 $M_{\odot}$\,pc$^{-2}$ below which we do not observe very thin, rotationally supported galactic disks.

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arXiv2020

Active galactic nuclei among polar-ring galaxies

Based on SDSS data, we consider the fraction of active galactic nuclei among polar-ring galaxies. We have found evidence for an excess of Seyfert galaxies and LINERs among polar-ring galaxies compared to ordinary objects. The observed nuclear activity of polar-ring galaxies may be associated with the accretion of gas from the region of the polar structures onto the central galaxies.

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arXiv2019

Edge-on galaxies in the Hubble Ultra Deep Field

We studied a sample of 58 edge-on spiral galaxies at redshifts $z \sim 1$ selected in the Hubble Ultra Deep Field. For all galaxies we analyzed the 2D brightness distributions in the $V_{606}$ and $i_{775}$ filters and measured the radial ($h_r$) and vertical ($h_z$) exponential scales of the brightness distribution. We obtained evidence that the relative thickness of the disks of distant galaxies, i.e., the ratio of the vertical scale height and radial scale length ($h_z/h_r$), on average, exceeds the relative thickness of the disks of nearby spiral galaxies. The vertical scale height $h_z$ of the stellar disks of galaxies shows no big changes at $z \leq 1$. The possibility of the evolution of the radial scale length $h_r$ for the brightness distribution with redshift is discussed.

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arXiv2018

New candidates to polar-ring galaxies from the Sloan Digital Sky Survey

Polar-ring galaxies (PRGs) are fascinating systems in which the central object (typically, an early-type galaxy) is encircled by a large-scale ring of stars, gas, and dust with almost perpendicular spin. PRGs are rare objects and their formation mechanism is not entirely clear. In this paper, we present a new sample of 31 candidates to PRGs identified in the Sloan Digital Sky Survey (SDSS). Using their stacked $gri$ images, we determined geometrical parameters of these galaxies (the position angle and the size of the host galaxy and the ring). We compare our sample objects to the previously known PRGs and discuss their general characteristics (the frequency of faint outer structures, the luminosity--size relation, and the distribution by the apparent angle between the ring and the host galaxy). Our main results are: (i) Central galaxies of PRGs follow the luminosity--size relation for ordinary galaxies. The ring components are located along the similar relation but with a larger scatter. This increasing scatter may be the result of a secondary origin of polar structures. (ii) At least half of PRGs show a ring component within 20$^\circ$ from the perpendicular orientation.

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arXiv2017

SDSS J170745+302056: a low surface brightness galaxy in a group

On the basis of the SDSS survey and spectral observations with the 6-m telescope of SAO RAS, we have peformed a detailed study of SDSS J170745+302056. By combination of its characteristics -- exponential surface brightness distribution, central surface brightness of stellar disk $μ_0(B) = 23.25\,^m/\square"$, blue colors, low metallicity and low star formation rate -- the galaxy is a typical low surface brightness spiral galaxy. Exponential scalelength of the galaxy is $\approx$3 kpc, its optical diameter exceeds 20 kpc. SDSS J170745+302056 is a member of a group of five galaxies and probably it is in interaction with UGC 10716. The existence of a large low surface brightness galaxy in such a dense environment is very unusual.

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arXiv2017

Measuring the X-shaped structures in edge-on galaxies

We present a detailed photometric study of a sample of 22 edge-on galaxies with clearly visible X-shaped structures. We propose a novel method to derive geometrical parameters of these features, along with the parameters of their host galaxies based on the multi-component photometric decomposition of galactic images. To include the X-shaped structure into our photometric model, we use the IMFIT package, in which we implement a new component describing the X-shaped structure. This method is applied for a sample of galaxies with available SDSS and Spitzer IRAC 3.6 $μ$m observations. In order to explain our results, we perform realistic $N$-body simulations of a Milky Way-type galaxy and compare the observed and the model X-shaped structures. Our main conclusions are as follows: (1) galaxies with strong X-shaped structures reside in approximately the same local environments as field galaxies; (2) the characteristic size of the X-shaped structures is about 2/3 of the bar size; (3) there is a correlation between the X-shaped structure size and its observed flatness: the larger structures are more flattened; (4) our $N$-body simulations qualitatively confirm the observational results and support the bar-driven scenario for the X-shaped structure formation.

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arXiv2017

Spatial environment of polar-ring galaxies from the SDSS

Based on SDSS data, we have considered the spatial environment of galaxies with extended polar rings. We used two approaches: estimating the projected distance to the nearest companion and counting the number of companions as a function of the distance to the galaxy. Both approaches have shown that the spatial environment of polar-ring galaxies on scales of hundreds of kiloparsecs is, on average, less dense than that of galaxies without polar structures. Apparently, one of the main causes of this effect is that the polar structures in a denser environment are destroyed more often during encounters and mergers with other galaxies.

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arXiv2016

Very Thin Disc Galaxies in The SDSS Catalog of Edge-on Galaxies

We study the properties of galaxies with very thin discs using a sample of 85 objects whose stellar disc radial-to-vertical scale ratio determined from photometric decomposition, exceeds nine. We present evidences of similarities between the very thin disc galaxies (VTD galaxies) and low surface brightness (LSB) disc galaxies, and conclude that both small and giant LSB galaxies may reveal themselves as VTD, edge-on galaxies. Our VTD galaxies are mostly bulgeless, and those with large radial scale length tend to have redder colors. We performed spectral observations of 22 VTD galaxies with the Dual Imaging Spectrograph on the 3.5m telescope at the Apache Point Observatory. The spectra with good resolution (R ~ 5000) allow us to determine the distance and the ionized gas rotation curve maximum for the galaxies. Our VTD galaxies have low dust content, in contrast to regular disc galaxies. Apparently, VTD galaxies reside in specific cosmological low-density environments and tend to have less connection with filaments. Comparing a toy model that assumes marginally low star formation in galactic discs with obtained gas kinematics data, we conclude that there is a threshold central surface density of about 88 Mo/pc**2, which we observe in the case of very thin, rotationally supported galactic discs.

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arXiv2015

Polar-bulge galaxies

Based on SDSS data, we have selected a sample of nine edge-on spiral galaxies with bulges whose major axes show a high inclination to the disk plane. Such objects are called polar-bulge galaxies. They are similar in their morphology to polar-ring galaxies, but the central objects in them have small size and low luminosity. We have performed a photometric analysis of the galaxies in the g and r bands and determined the main characteristics of their bulges and disks. We show that the disks of such galaxies are typical for the disks of spiral galaxies of late morphological types. The integrated characteristics of their bulges are similar to the parameters of normal bulges. The stellar disks of polar-bulge galaxies often show large-scale warps, which can be explained by their interaction with neighboring galaxies or external accretion from outside.

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arXiv2015

Does the stellar disc flattening depend on the galaxy type?

We analyze the dependence of the stellar disc flatness on the galaxy morphological type using 2D decomposition of galaxies from the reliable subsample of the Edge-on Galaxies in SDSS (EGIS) catalogue. Combining these data with the retrieved models of the edge-on galaxies from the Two Micron All Sky Survey (2MASS) and the Spitzer Survey of Stellar Structure in Galaxies (S$^4$G) catalogue, we make the following conclusions: (1) The disc relative thickness $z_0/h$ in the near- and mid-infrared passbands correlates weakly with morphological type and does not correlate with the bulge-to-total luminosity ratio $B/T$ in all studied bands. (2) Applying an 1D photometric profile analysis overestimates the disc thickness in galaxies with large bulges making an illusion of the relationship between the disc flattening and the ratio $B/T$. (3) In our sample the early-type disc galaxies (S0/a) have both flat and "puffed" discs. The early spirals and intermediate-type galaxies have a large scatter of the disc flatness, which can be caused by the presence of a bar: barred galaxies have thicker stellar discs, on average. On the other hand, the late-type spirals are mostly thin galaxies, whereas irregular galaxies have puffed stellar discs.

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arXiv2014

The Catalog of Edge-on Disk Galaxies from SDSS. Part I: the catalog and the Structural Parameters of Stellar Disks

We present a catalog of true edge-on disk galaxies automatically selected from the Seventh Data Release (DR7) of the Sloan Digital Sky Survey. A visual inspection of the $g$, $r$ and $i$ images of about 15000 galaxies allowed us to split the initial sample of edge-on galaxy candidates into 4768 (31.8% of the initial sample) genuine edge-on galaxies, 8350 (55.7%) non-edge-ons, and 1865 (12.5%) edge-on galaxies not suitable for simple automatic analysis because these objects show signs of interaction, warps, or nearby bright stars project on it. We added more candidate galaxies from RFGC, EFIGI, RC3, and Galaxy Zoo catalogs found in the SDSS footprints. Our final sample consists of 5747 genuine edge-on galaxies. We estimate the structural parameters of the stellar disks (the stellar disk thickness, radial scale length, and central surface brightness) in the galaxies by analyzing photometric profiles in each of the g, r, and i images. We also perform simplified 3-D modeling of the light distribution in the stellar disks of edge-on galaxies from our sample. Our large sample is intended to be used for studying scaling relations in the stellar disks and bulges and for estimating parameters of the thick disks in different types of galaxies via the image stacking. In this paper we present the sample selection procedure and general description of the sample.

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arXiv2014

Mirages in galaxy scaling relations

We analyzed several basic correlations between structural parameters of galaxies. The data were taken from various samples in different passbands which are available in the literature. We discuss disc scaling relations as well as some debatable issues concerning the so-called Photometric Plane for bulges and elliptical galaxies in different forms and various versions of the famous Kormendy relation. We show that some of the correlations under discussion are artificial (self-correlations), while others truly reveal some new essential details of the structural properties of galaxies. Our main results are as follows: (1) At present, we can not conclude that faint stellar discs are, on average, more thin than discs in high surface brightness galaxies. The ``central surface brightness -- thickness'' correlation appears only as a consequence of the transparent exponential disc model to describe real galaxy discs. (2) The Photometric Plane appears to have no independent physical sense. Various forms of this plane are merely sophisticated versions of the Kormendy relation or of the self-relation involving the central surface brightness of a bulge/elliptical galaxy and the Sersic index n. (3) The Kormendy relation is a physical correlation presumably reflecting the difference in the origin of bright and faint ellipticals and bulges. We present arguments that involve creating artificial samples to prove our main idea.

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arXiv2013

Pitch angle variations in spiral galaxies

We present a detailed photometric study and measurements of spiral arm pitch angles for a sample of 50 non-barred or weakly barred grand-design spiral galaxies selected from Sloan Digital Sky Survey. In order to find pitch angles, we used a new method based on the window Fourier analysis of their images. This method allows us not only to infer the average pitch angle, but to obtain its value as a function of galactocentric radius as well. Our main results are as follows: (1) Spiral arms of most galaxies cannot be described by a single value of the pitch angle. About 2/3 of galaxies demonstrate pitch angle variations exceeding 20%. In most galaxies in the sample their pitch angle decreases by increasing the distance from the centre. (2) Pitch angle variations correlate with the properties of galaxies - with the shape of the surface brightness distribution (envelope-type or truncated disc), and with the sign of stellar disc colour gradient. (3) More luminous and bright bulges produce more tightly wound spiral arms, that is in agreement with current models for spiral arms formation.

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arXiv2011

Pitch angles of distant spiral galaxies

We have studied the pitch angles of spiral arms for 31 distant galaxies at z~0.7 from three Hubble Deep Fields (HDF-N, HDF-S, HUDF). Using the pitch angle - rotation velocity relation calibrated from nearby galaxies, we have estimated the rotation velocities of galaxies from the deep fields. These estimates have a low accuracy (~50 km/s), but they allow low-mass and giant galaxies to be distinguished. The Tully-Fisher relation constructed using our velocity estimates shows satisfactory agreement with the actually observed relations for distant galaxies and provides evidence for the luminosity evolution of spiral galaxies.

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arXiv2011

Statistics of interacting galaxies at z~0.7

We present the results of our analysis of the frequencies of galaxies with tidal tails and M51-type galaxies in several deep fields of the Hubble Space Telescope (HDF-N, HDF-S, HUDF, GOODS, GEMS). In total, we have found about seven hundred interacting galaxies at redshifts z<1.5 in these fields. At z<0.7, the observed space densities of galaxies with tidal structures and M51-type galaxies have been found to increase as $\propto (1+z)^m$, where m~2.6. According to our estimates, over the last 6-7 Gyr, i.e., at z<0.7, about a third of the galaxies with M(B)<-18 mag must have undergone strong gravitational perturbations and mergers and ~1/10-1/5 of the galaxies have accreted relatively low-mass nearby satellites typical of M51-type galaxies. The possible decrease in the timescale on which a distant galaxy appears peculiar with growing z can increase considerably the estimated rate of mergers.

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