arXiv subjects

D. I. Makarov

Publications and source records attributed to D. I. Makarov.

At least 19 recordsLinked to original sources

arXiv2025

Orientation of galaxy spins relative to filaments of the large-scale structure of the Universe

The theory of galaxy formation posits a clear correlation between the spin of galaxies and the orientation of the elements of the large-scale structure of the Universe, particularly cosmic filaments. A substantial number of observational and modelling studies have been undertaken with the aim of identifying the dependence of spin orientation on the components of the large-scale structure. However, the findings of these studies remain contradictory. In this paper, we present an analysis of the orientation of the spins of 2 861 galaxies with respect to the filaments of the large-scale structure of the Universe. All galaxies in our sample have an inclination to the line of sight greater than 85 degrees, enabling an unambiguous determination of the spin axis direction in space. We investigate the alignment of galaxy spin axes relative to cosmic web filaments as a function of various properties for galaxies. Our results reveal a statistically significant tendency for the galaxy spin axes to align along the filament axes of the large-scale structure.

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arXiv2023

Search for the edge-on galaxies using an artificial neural network

We present an application of an artificial neural network methodology to a modern wide-field sky survey Pan-STARRS1 in order to build a high-quality sample of disk galaxies visible in edge-on orientation. Such galaxies play an important role in the study of the vertical distribution of stars, gas and dust, which is usually not available to study in other galaxies outside the Milky Way. We give a detailed description of the network architecture and the learning process. The method demonstrates good effectiveness with detection rate about 97\% and it works equally well for galaxies over a wide range of brightnesses and sizes, which resulted in a creation of a catalogue of edge-on galaxies with $10^5$ of objects. The catalogue is published on-line with an open access.

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arXiv2023

Satellites around Edge-on Galaxies. I. Dynamical Masses

We have undertaken a search for satellites around edge-on galaxies in the EGIPS catalog, which contains 16551 objects with declinations above -30 deg. We searched for systems with a central galaxy dominating in brightness by at least 1 mag compared to its companions. As a result, we discovered 1097 candidate satellites around 764 EGIPS galaxies with projected distances less than 500 kpc and a radial velocity difference less than 300 km/s. Of these, 757 satellites around 547 central galaxies have radial velocity accuracies higher than 20 km/s and satisfy the gravitationally bound condition. The ensemble of satellites is characterized by an average projected distance of 84 kpc and an average radial velocity dispersion of 103 km/s. Treating small satellites as test particles moving on isotropic orbits around central EGIPS galaxies, we determined the projected (orbital) masses of the edge-on galaxies. Within the luminosity range of 1.3*10^10 to 42*10^{10} Lsun, the total mass of the systems is well described by a linear dependence log(Mp)~0.88*log( g) with an average total mass-to-$K$-band luminosity equal to 17.5+-0.8 Msun/Lsun, which is typical for nearby spiral galaxies such as the Milky Way, M 31 and M 81.

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arXiv2023

Gradients of metallicity and age of stars in the dwarf spheroidal galaxies KKs3 and ESO269-66

We compare the properties of the stellar populations of the globular clusters and field stars in two dwarf spheroidal galaxies (dSphs): ESO269-66, a near neighbor of the giant S0 galaxy NGC 5128, and KKs3, one of the few extremely isolated dSphs within 10 Mpc. The histories of star formation in these galaxies are known from previous work on deep stellar photometry using images from the Hubble Space Telescope (HST). The age and metal content for the nuclear globular clusters in KKs3 and ESO269-66 are known from literature spectroscopic studies: T=12.6 billion years, [Fe/H]=-1.5 and -1.55 dex. We use the Sersic function to construct and analyze the profiles of the surface density of the stars with high and low metallicities (red and blue) in KKs3 and ESO269-66, and show that (1) the profiles of the density of red stars are steeper than those of blue stars, which is indicative of gradients of metallicity and age in the galaxies, and (2) the globular clusters in KKs3 and ESO269-66 contain roughly 4 and 40%, respectively, of all the old stars in the galaxies with metallicities [Fe/H]~-1.5 to -1.6 dex and ages of 12-14 billion years. The globular clusters are, therefore, relicts of the first, most powerful bursts of star formation in the central regions of these objects. It is probable that, because of its isolation, KKs3 has lost a smaller fraction of old low-metallicity stars than ESO269-66.

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arXiv2021

Database For Studying Edge-on Galaxies

We present a database created within the project on studying edge-on galaxies. These galaxies provide a unique opportunity to study the three-dimensional distribution of the matter in galaxy disks, which is extremely important for analyzing the influence of internal and external factors on the evolution of galaxies. For the moment, extensive observed material has been accumulated on the kinematics and photometry of such galaxies. The database is designed to organize information, make it easier to visualize, and to improve works on studying this type of objects. The database combines information from previous catalogs on edge-on galaxies and data from current projects; provides access to astrometric and photometric data; carries out interconnection with other databases. The present paper describes the structure and web-access to the database: https://www.sao.ru/edgeon/

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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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arXiv2021

Spatial segregation impact on star formation in nearby dwarf spheroidal galaxies

Using our HST/ACS observations of the recently found isolated dwarf spheroidal galaxies, we homogeneously measured their star formation histories. We determined star formation rate as a function of time, as well as age and metallicity of the stellar populations. All objects demonstrate complex star formation history, with a significant portion of stars formed 10-13 Gyr ago. Nevertheless, stars of middle ages (1-8 Gyr) are presented. In order to understand how the star formation parameters influence the evolution of dSphs, we also studied a sample of nearest dSphs in different environment: isolated (d < 2 Mpc); beyond the Local Group virial radius (but within the Local Group zero velocity sphere); and the satellites of M 31 located within the virial zone (300 kpc). Using archival HST/ACS observations, we measured their star formation histories. A comparative analysis of the parameters obtained allow us to distinguish a possible effect of the spatial segregation on the dSphs evolution scenario.

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arXiv2018

Void galaxies in the nearby Universe. I. Sample description

The main goal of this work is to form a large, deep and representative sample of dwarf galaxies residing in voids of the nearby Universe. The formed sample is the basement for the comprehensive mass study of the galaxy content, their evolutionary status, clustering and dynamics with respect to their counterparts residing in more typical, denser regions and for study of void small-scale substructures. We present 25 voids over the entire sky within 25 Mpc from the Local Group. They are defined as groups of lumped empty spheres bounded by `luminous' galaxies with the absolute K-band magnitudes brighter than -22.0. The identified void regions include the Local Void and other known nearby voids. The nearest nine voids occupy a substantial part of the Local Volume. Of the total number of 6792 cataloged galaxies in the considered volume, 1354 objects fall into 25 nearby voids. Of this general void galaxy sample, we separate the sub-sample of `inner' void galaxies, residing deeper in voids, with distances to the nearest luminous galaxy DNN > 2.0 Mpc. The `inner' galaxy sample includes 1088 objects, mostly dwarfs with MB distribution peaked near -15.0 and extending down to -7.5 mag. Of them, 195 fall in the Local Volume (space within R=11 Mpc). We present the general statistical properties of this Nearby Void Galaxy sample and discuss the issues related to the sample content and the prospects of its use.

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arXiv2018

Nearby void dwarf galaxies: recent results, the ongoing project and prospects

Properties of dwarf galaxies formed and evolved in the lowest density environment remain largely unexplored and poorly understood. Especially this concerns the low-mass end (M_bar < 10^9 Mo). We overview the results of systematic study of a hundred void dwarfs from the nearby Lynx-Cancer void. We describe the ongoing project aiming to form Nearby Void galaxy sample (R < 25 Mpc) over the whole sky. 1354 objects with distances less than 25 Mpc fall within 25 voids delineated by 460 luminous galaxies/groups. The void major sizes range from 13 to 37 Mpc. 1088 of 1354 void galaxies reside deeply in voids, having distances to the nearest luminous neighbour of 2-11 Mpc. 195 nearest void galaxies reside in the Local Volume. We summarize the main statistical properties of the new sample and outline the prospects of study of both, the void dwarf properties and the fine structure of voids.

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arXiv2018

Morphological properties of galaxies in different Local Volume environments

We consider an all-sky sample of 1029 Local Volume (LV) galaxies situated within a distance of 11 Mpc. Their majority have precise distances, estimates of hydrogen mass fraction and star-formation rate derived from far-ultraviolet or Halpha fluxes. To describe an environment, we attribute two dimensionless values: the density contrast created by the most significant neighbour and the local density contrast produced by all neighbours within a separation of 1 Mpc. The hydrogen mass fraction exhibits a weak effect of HI deficiency being the most pronounced for dwarf irregular galaxies. The specific star-formation rate (sSFR) is more sensitive to the environment than the hydrogen mass fraction. Almost all (99 per cent) LV galaxies have their sSFR below -9.4 dex (1/yr). We notice that irregular dwarfs as well as late-type bulgeless galaxies are capable to reproduce their stellar mass with the observed sSFR over the cosmic time. Thus, the transformation of gas into stars in dIrs and spiral disks is rather sluggish unlike that in E, S0, dSph galaxies, whose star-formation history has been stormy and short. Scatter of SFR(Halpha)-to-SFR(FUV) ratio increases from Sc, Sd, Sm galaxies towards BCD, Im, Ir types that favours the idea of bursty star formations in low-mass galaxies. However, this bursty activity is caused rather by internal processes than by an external tidal action. A fraction of quenched E, S0, dSph galaxies increases from ~5 per cent in the field up to ~50 per cent in the densest regions.

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arXiv2018

The Tully-Fisher relation for flat galaxies

We construct a multiparametric Tully-Fisher (TF) relation for a large sample of edge-on galaxies from the Revised Flat Galaxy Catalog using HI data from the EDD database and parameters from the EGIS catalog. We incorporate a variety of additional parameters including structural parameters of edge-on galaxies in different bandpasses. Besides the rotation curve maximum, only the HI-to-optical luminosity ratio and optical colours play a statistically significant role in the multiparametric TF relation. We are able to decrease the standard deviation of the multiparametric TF relation down to 0.32 mag, which is at the level of best modern samples of galaxies used for studies of the matter motion in the Universe via the TF-relation.

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arXiv2017

Serendipitous discovery of a faint dwarf galaxy near a Local Volume dwarf

A faint dwarf irregular galaxy has been discovered in the HST/ACS field of LV J1157+5638. The galaxy is resolved into individual stars, including the brightest magnitude of the red giant branch. The dwarf is very likely a physical satellite of LV J1157+5638.The distance modulus of LV J1157+5638 using the tip of the red giant branch (TRGB) distance indicator is 29.82+-0.09 mag (D = 9.22+-0.38 Mpc). The TRGB distance modulus of LV J1157+5638 sat is 29.76+-0.11 mag (D = 8.95+-0.42 Mpc). The distances to the two galaxies are consistent within the uncertainties. The projected separation between them is only 3.9 kpc. LVJ1157+5638 has a total absolute V-magnitude of -13.26+-0.10 and linear Holmberg diameter of 1.36 kpc, whereas its faint satellite LV J1157+5638 sat has M_V = -9.38+-0.13 mag and Holmberg diameter of 0.37 kpc. Such a faint dwarf was discovered for the first time beyond the nearest 4 Mpc from us. The presence of main sequence stars in both galaxies unambiguously indicates the classification of the objects as dwarf irregulars (dIrrs) with recent or ongoing star formation events in both galaxies.

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arXiv2016

Unusual void galaxy DDO68: implications of the HST resolved photometry

DDO68 (UGC5340) is an unusual dwarf galaxy with extremely low gas metallicity (12+log(O/H) = 7.14) residing in the nearby Lynx-Cancer void. Despite its apparent isolation, it shows both optical and HI morphological evidence for strong tidal disturbance. Here, we study the resolved stellar populations of DDO68 using deep images from the HST archive. We determined a distance of 12.75+-0.41 Mpc using the tip of the red giant branch (TRGB). The star formation history reconstruction reveals that about 60 per cent of stars formed during the initial period of star formation, about 12-14 Gyr ago. During the next 10 Gyr DDO68 was in the quenched state, with only slight traces of star formation. The onset of the most recent burst of star formation occurred about 300 Myr ago. We find that young populations with ages of several million to a few hundred million years are widely spread across various parts of DDO68, indicating an intense star formation episode with a high mean rate of 0.15 Msun/yr. A major fraction of the visible stars in the whole system (~80 per cent) have low metallicities: Z = Zsun/50 - Zsun/20. The properties of the northern periphery of DDO68 can be explained by an ongoing burst of star formation induced by the minor merger of a small, gas-rich, extremely metal-poor galaxy with a more typical dwarf galaxy. The current TRGB-based distance of DDO68 implies a total negative peculiar velocity of ~500 km/s.

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arXiv2016

Extremely metal-poor galaxy DDO 68: the LBV, H-alpha shells and the most luminous stars

The paper presents new results of the ongoing study of the unusual Lynx-Cancer void galaxy DDO 68 with record-low-metallicity regions (12+log(O/H) ~7.14) of the current star formation (SF). They include: a) a new spectrum and photometry with the 6-m SAO RAS telescope (BTA) for the Luminous Blue Variable (LBV = DDO68-V1). Photometric data sets are complemented with those based on the Sloan Digital Sky Survey (SDSS) and the Hubble Space Telescope (HST) archive images; b) the analysis of the DDO~68 supergiant shell (SGS) and the prominent smaller H-alpha arcs/shells visible at the HST image coupled with kinematics maps in H-alpha obtained with the Fabry-Perot interferometer (FPI) at the BTA; c) the list of identified at the HST images of about 50 most luminous stars (-9.1 < M_V < -6.0 mag) related to star-forming regions with the known extremely low O/H. This is intended to pave the path for the actual science with the next generation of giant telescopes. We confirm the earlier hints on significant variations of the LBV optical light deriving its amplitude of dV > 3.7~mag for the first time. New data suggest that in 2008--2010 the LBV reached M_V = --10.5 and probably underwent a giant eruption. We argue that the structure of star-forming complexes along the SGS (`Northern Ring') perimeter provides evidence for the sequential induced SF episodes caused by the shell gas instabilities and gravitational collapse. The variability of some DDO~68 luminous extremely metal-poor stars can be monitored with medium-size telescopes at sites with superb seeing.

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arXiv2016

Star formation history of And XVIII: a dwarf spheroidal galaxy in isolation

We present a photometric study of the Andromeda XVIII dwarf spheroidal galaxy associated with M31, and situated well outside of the virial radius of the M31 halo. The galaxy was resolved into stars with Hubble Space Telescope/Advanced Camera for Surveys revealing the old red giant branch and red clump. With the new observational data we determined the Andromeda XVIII distance to be D = 1.33+-0.08 Mpc using the tip of red giant branch method. Thus, the dwarf is situated at the distance of 579 kpc from M31. We model the star formation history of Andromeda XVIII from the stellar photometry and Padova theoretical stellar isochrones. An ancient burst of star formation occurred 12-14 Gyr ago. There is no sign of recent/ongoing star formation in the last 1.5 Gyr. The mass fractions of the ancient and intermediate age stars are 34 and 66 per cent, respectively, and the total stellar mass is 4.2x10^6 Msun. It is probable that the galaxy has not experienced an interaction with M31 in the past. We also discuss star formation processes of dSphs KKR 25, KKs 03, as well as dTr KK 258. Their star formation histories were uniformly measured by us from HST/ACS observations. All the galaxies are situated well beyond the Local Group and the two dSphs KKR 25 and KKs 03 are extremely isolated. Evidently, the evolution of these objects has proceeded without influence of neighbours.

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arXiv2016

Ultra-Flat Galaxies Selected from RFGC Catalog. I. The Sample Properties

We used the Revised Flat Galaxy Catalog (RFGC) to create a sample of ultra-flat galaxies (UFG) covering the whole northern and southern sky apart from the Milky Way zone. It contains 817 spiral galaxies seen edge-on, selected into the UFG sample according to their apparent axial ratios $(a/b)_B\geq10.0$ and $(a/b)_R\geq8.53$ in the blue and red bands, respectively. Within this basic sample we fixed an exemplary sample of 441 UFG galaxies having the radial velocities of $V_{LG} < 10000$ km s$^{-1}$, Galactic latitude of $\mid b\mid>10^{\circ}$ and the blue angular diameter of $a_B > 1.0^{\prime}$. According to the Schmidt test the exemplary sample of 441 galaxies is characterized by about (80-90)% completeness, what is quite enough to study different properties of the ultra-flat galaxies. We found that more than 3/4 of UFGs have the morphological types within the narrow range of $T= 7\pm1$, i.e. the thinnest stellar disks occur among the Scd, Sd, and Sdm types. The average surface brightness of UFG galaxies tends to diminish towards the flattest bulge-less galaxies. Regularly shaped disks without signs of asymmetry make up about 2/3 both among all the RFGC galaxies, and the UFG sample objects. About 60% of ultra-flat galaxies can be referred to dynamically isolated objects, while 30% of them probably belong to the scattered associations (filaments, walls), and only about 10% of them are dynamically dominating galaxies with respect to their neighbours.

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arXiv2015

6-meter telescope observations of three dwarf spheroidal galaxies with very low surface brightness

Dwarf spheroidal galaxies (dSphs) are mostly investigated in the Local Group. DSphs are difficult targets for observations because of their small size and very low surface brightness. Here we measure spectroscopic and photometric parameters of three candidates for isolated dSphs, KKH65=BTS23, KK180, and KK227, outside the Local Group. The galaxies are found to be of low metallicity and low velocity dispersion. They are among the lowest surface brightness objects in the Local Universe. According to the measured radial velocities, metallicities, and structural and photometric parameters, KKH65 and KK227 are representatives of the ultra-diffuse quenched galaxies. KKH65 and KK227 belong to the outer parts of the groups NGC3414 and NGC5371, respectively. KK180 is located in the Virgo cluster infall region.

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arXiv2015

New radial velocities for dwarf galaxies in the Local Volume

Radial velocities measured with the 6-meter telescope are given for 5 faint dwarf galaxies. All of these galaxies are confirmed as very nearby objects. Two of them, KK135 (dIr) and UGC 1703 (dSph/dTr), are local isolated dwarfs, and the three others, UGCA 127sat (dIr), NGC 2683dw1 (dIr), and NGC891dwA (dTr), belong to companions of nearby massive spirals.

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