Important scientific achievements



1) A new bright galaxy of the Local Group VV124 (UGC4879) is found. The last discovery of such a bright galaxy of the Local Group was made 40 years ago. Taking into account all the works of recent years on the search for nearby galaxies, it can be stated that the VV124 is the latest found bright galaxy belonging to the Local Group of galaxies.


Kopylov A.I., Tikhonov N.A., Fabrika S.N., Drozdovsky I.O., Valeev A.F., MNRAS Lett, V. 387, Issue 1, L45, 2008.

Tikhonov N.A., Fabrika S.N., Sholukhova O.N., Kopylov A.I., Astronomy Letters, V. 36, Issue 5, p. 309,  2010.



vv124

Fig. 1.  Galaxy  VV124 (BTA image).





2) Within a few decades, there was a popular hypothesis about the possibility for primary young galaxies with low metalicity and the first wave of star formation in the history of these galaxies to be found in the relatively close neighborhood of our galaxy. As a sample of galaxies of this type the 1Zw18 galaxy has been always called for. Using the Hubble Space Telescope images, we carried out stellar photometry for 1Zw18 and for the first time we had found in this galaxy red giants with the age of several billion years, which immediately rejected the hypothesis that the galaxy was young.


Tikhonov N.A., Astronomy Letters, V.33, Iss.3, p.137, 2007.


1Zw18

Fig. 2. Galaxy 1Zw18 (HST image).





3) Dynamical and photometrical (near-infrared, in K-band) characteristics of 183 groups and clusters of galaxies located in the regions of superclusters of galaxies Hercules, Leo, Ursa Major, Bootes, Corona Borealis and outside superclusters having radial velocities in the interval 0.012<z<0.09 (+ Virgo cluster) based on the archival data from the SDSS, 2MASX, NED catalogues are determined. The IR-luminosity of the systems of galaxies mainly corresponding to the luminosity of old stars from early-type galaxies allows to the first approximation to estimate their masses according to the correlation between dynamical mass and IR-luminosity. For systems of galaxies in the regions of the Hercules and  Leo superclusters the dwarf-to-giant ratio of galaxies in the r-band is evaluated, and it is found that this ratio increases with increasing X-ray luminosity at log LX > 43.5 erg/s.


Kopylova F.G., Kopylov A.I., Ast. Bull. 64, 1, 2009.
Kopylova F.G., Kopylov A.I., 2011, Astron. Lett., 37, 219, 2011.
Kopylova F.G., Astroph. Bull. 68, 253, 2013.
Kopylova F.G., Kopylov A.I., Astron. Lett., 39, 1, 2013.
Kopylova F.G., Kopylov A.I., Ast. Bull. 70, 123, 2015.


fig2






4) Using the data of catalogues of SDSS DR8 we investigated the peculiar motions of groups and clusters of galaxies in the regions of Hercules, Leo, Bootes, Ursa Major, Corona Borealis, A2142, Z5029/A1424, A1190, A1750/A1809. For this purpose, we compiled a samples of ealy-type galaxies in them and determined the fundamental plane distances and peculiar velocities. For all superclusters of galaxies is Hubble's law between the radial velocity and distance obtained by the fundamental plane of early-type galaxies. Within their regions the significant peculiar motion rms deviations along the line of sight 736±50 km/s Hercules, 625±70 km/s Leo, 757±70 km/s Bootes, 290±120 km/s Ursa Major, 652±50 km/s Corona Borealis, 1366±170 km/s Z5029/A1424. The pecular motions of clusters we found in the Corona Borealis region are characterized by gravitational coupling of this supercluster with the supercluster A2142. The rms deviation of peculiar velocities of 20 clusters of galaxies outside the largest structures, is equal to 0±20 km/s.

Kopylova F.G., Kopylov A.I., Astron. L. 33, 211, 2007.
Kopylova F.G., Kopylov A.I., 2014, Astron. L. 40, 595, 2014.
Kopylova F.G., Kopylov A.I., Astrophys. Bull. 72, 363, 2017.


fig3

Fig. 4. The map of distribution of galaxies and clusters in the region of Hercules and Leo superclusters with radial velocities in the range of cz = 8000–13000 km/s.












5) The study was performed of four complex (bimodal) Abell clusters with difference of radial velocities between the subclusters of about 3000 km/s, which may be due either to the gravitational interaction between very massive clusters at a collision on the line close to the line-of-sight or the projection along the line-of-sight of non-connected clusters. Using observational data from the 1-m telescope of SAO RAS and data of the SDSS catalogue we measured photometric relative distances (by the Kormendy relation and the fundamental plane) and revealed the structure of clusters A1035, A1569, A1775 and A1831. It is found that subclusters in these clusters are not bound gravitationally, and for them the Hubble law is obeyed.

Kopylov A.I., Kopylova F.G., Ast. Bull. 62, 311, 2007.
Kopylov A.I., Kopylova F.G., Ast. Bull. 64, 207, 2009.
Kopylov A.I., Kopylova F.G., Ast. Bull. 65, 205, 2010.
Kopylov A.I., Kopylova F.G., Ast. Bull. 67, 17, 2012.


fig4

Fig. 5. The Hubble diagram (velocity [zspec] – distance [zphot]) is shown for four bimodal clusters of galaxies (A-components to left, B-components to right), and for the cluster A1589, the nearest rich neighbour (12 Mpc) of the cluster A1569A.








6) The dependence between the physical parameters of low-mass spiral and irregular galaxies is found. Based on the stellar photometry of the Hubble Space Telescope images in 53 low-mass spiral and irregular galaxies, young (supergiants) and old (red giants) star subsystems are identified and their spatial dimensions and metallicity of the red giants are determined. For the first time a well-defined correlation was found between the metallicity of red giants and the difference in the sizes of star subsystems of different ages. The resulting correlation is interpreted as a result of the combined effect of two relationships:1) between the mass of galaxies and the metallicity of stars; 2) between the change in size of subsystem stars and the evolution time of galaxies, where the change in the metallicity of galaxies is taken as a time scale.


Tikhonov N.A., ASPCS,  510,  488, 20.

53

Fig. 6. Diagram of the relationship between the size difference (R-B) of the red giant (R) subsystems and the blue supergiants (B) and the metallicity of the red giants [Fe/H] of the same galaxies. The dependence found can be interpreted as an increase in the size of the star subsystems of irregular galaxies during their evolution.





7) Stellar photometry was performed from the images of the Hubble Space Telescope on 105 irregular or low-mass spiral galaxies.Distances to the galaxies were determined by the TRGB method and metallicities of old stars (red giants) were measured. The index of metallicity of young stars is taken to be the color index (V-I) of the branch of red supergiants, since it depends on the metallicity of the stars.
Basing on the obtained results, a diagram of the relationship between the metallicities of young and old stars is constructed. A good correspondence between the metallicities compared indicates that the main process of saturation of galaxies with metals occurred at the early stages of their evolution, and the possible merge of galaxies with small metal intergalactic gas clouds had an insignificant effect on the change in the metallicity of the galaxies
.

Tikhonov N.A., Ast. Bull., 73,  22, 2018.

105










8) For 84 groups of galaxies with σ < 420 km/s by plotting (ΔM1,4) magnitude gap between the first and fourth brightest galaxies and the concentration of galaxies (Σ5) determined from the fifth galaxy from the center, we have identified areas of location of «young» and «old» systems of galaxies. We have estimated the dynamic ages of the groups of galaxies comparing the luminosity of the brightest galaxy and the magnitude gap (ΔM1,4) with the theoretical model calculations (Raouf et al., 2014, MNRAS, 442, 1578). A probability that the selected groups belong to the category of «old» groups or «young» is equal 50%. It is found that the fraction of early-type galaxies in systems is not dependent neither on concentration of galaxies nor on mass or total luminosity and luminosity in X-ray.


Kopylova F. G., Kopylov A. I., Ast.Bull., 72,  100
, 2017.



Fig. 8. Magnitude gap ΔM1,4 as function of the concentration of galaxies. Galaxy groups with z < 0.027 σ < 420 km/s are shown by filled circles, those with z > 0.027 σ < 420 km/s by open circles, and the dots show the rich galaxy clusters with σ > 420 km/s. The large triangles show the dynamically «old» with a probability higher than 50% galaxy systems, and the large circles show the dynamically «young» ones with the same probability. A straight line corresponding ΔM1,4 = 2.5 separates the candidates in the oldest groups of galaxies «fossil» groups.





9) We have developed a new method for determining the size of galaxy clusters, the region with a radius of Rh (or Rsp) (>R200), from the cumulative distribution of the number of galaxies depending on the squared clustercentric distance, where Rh (or Rsp) radius of apocenter of orbits of galaxies. This allowed to determine for the systems of galaxies the total K-luminosity and the number of galaxies corrected for the background. K-luminosity, effective radius containing either half of the luminosity, or half the number of galaxies and dispersion of radial velocities of galaxy systems form a Fundamental plane (FP) LK = Re0.71×σ1.33. We also built the FP in the X-ray, LX = Re1.26×σ2.70. In addition, we obtained that the form of FP clusters consistent with the form of the FP of early-type galaxies in the r (SDSS) filter.


Kopylova F. G., Kopylov, A. I., Ast.Bull., 71, 129, 2016.



Fig. 9. The fundamental plane of early-type galaxies (red circles) and group and clusters of galaxies (blue circles) vs. the long axis logRe. The effective radius Re of clusters of galaxies is determined as radius containing half of the galaxies.










10) In order to study the star formation rate, morphological composition and other characteristics in the outskirts of clusters of galaxies, we have compiled a sample of the 27 clusters of galaxies with the following parameters: 0.020 < z < 0.045 σ > 400 km/s. For them, we measured by archived data SDSS DR7-8, 2MASX, NED catalogues dynamic characteristics and determined the nearest outskirts in units of radius R200 (of radius, within which the density in the cluster exceeds the critical density of the Universe 200 times), and in units of the radius Rsp~1.5×R200 (apocenter of the orbits of galaxies) found by us on the observed profile of clusters of galaxies.



Kopylova F. G., Kopylov, A. I., Ast.Bull., 73, ??, 2018.




Fig.10. Distribution of galaxies in the cluster A2040 (z = 0.045, σ = 589 /). The upper left figure shows the deviation of radial velocities of galaxies members of clusters and galaxies attributed to the background from the average radial velocity of the cluster, depending on the squared clustercentric radius. The lower left figure the integral distribution of the number of galaxies depending oh the squared clustercentric radius. The upper right figure  the location of galaxies in sky plane in equatorial coordinates. The lower right figure the histrogram of line-of-sight velocities of all galaxies within R200 (the solid line shows the Gaussian corresponding to the dispersion of line-of-sight velocities). The blue dashed line shows radius R200, the red dash-dotted line  radius Rsp.







11) For clusters of galaxies A1656 (Coma), A1139, A1314 (Leo supercluster), A2040, A2052, A2107 (Hercules supercluster) the fraction of early-type galaxies on the «red sequence», determined by the color-magnitude relation, is measured. It is obtained that this fraction – on the outskirts, outside the Rsp – is minimal and corresponds to the value for the field 0.24±0.01, which has the same range of radial velocities, the size 300 arcminutes and the coordinates of the center: 14h.5, 35o.




Kopylova F. G., Kopylov, A I., Ast.Bull., 73, 2, ??, 2018.




Fig.11. Phase-space diagram (velocity radius) of cluster A1656. The velocity is the ratio of the difference of the radial velocities of galaxies and mean radial velocity of the cluster to its dispersion of radial velocities. The radius R/R200 is the clustercentric distance of galaxy, normalized to a radius of  R200. Red circles show the «red sequences» early-type galaxies. Cluster galaxies are selected within 2.7 σ.