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We study the outskirts ($R, Comment: 16 pages, 7 figures, 3 tables

We investigate the specific star formation rate of galaxies as a function of distance from the cluster centre (R 3R200) in a sample of 40 groups and clusters of galaxies of the local Universe. Using the SDSS Data Release 10, we find that the fraction of galaxies with quenched star formation is maximal in the central regions of the galaxy clusters and equals, on the average, 0.81; it decreases to 0.44 outside of the projected "splashback" radius Rsp, which we found from the observed profile of galaxy cluster, but still remains higher than that in the field by 27%.

Based on the SDSS data, the properties of galaxies with quenched star formation (QGs) within the "splashback"-radius of galaxy clusters $R_{\rm sp}$ and beyond it have been studied. We used a sample of 40 groups and galaxy clusters and a sample of field galaxies at $0.02, Comment: 11 pages, 5 figures

We investigate the variation of the fraction of galaxies with suppressed star formation (MK < −21 . m 5) and early-type galaxies (fracE) of the “red sequence” along the projected radius in six galaxy clusters:Coma (A1656), A1139, and A1314 in the Leo supercluster region (z ≈ 0.037) and A2040, A2052, A2107 in the Hercules supercluster region (z ≈ 0.036). According to SDSS (DR10) data, fracE is the highest in the central regions of galaxy clusters and it is, on the average, equal to 0.62 ± 0.03, whereas in the 2–3R/R200c interval and beyond the Rsp ≈ 0.95 ± 0.04 R200m radius that we inferred from the observed profile fracE is minimal and equal to 0.25 ± 0.02. This value coincides with the estimate fracE = 0.24 ± 0.01 that we inferred for field galaxies located between the Hercules and Leo superclusters at the same redshifts. We show that the fraction of galaxies with suppressed star formation decreases continuously with cluster radius from 0.87 ± 0.02 in central regions down to 0.43 ± 0.03 in the 2–3 R/R200c interval and beyond Rsp, but remains, on the average, higher than 26% than the corresponding fraction for field objects. This decrease is especially conspicuous in the galaxy mass interval log M* [M⊙] = 9.5–10. We found that galaxies with ongoing star formation have average clustercentric distances 1.5–2.5 R/R200c and that their radial-velocity dispersions are higher than those of galaxies with suppressed star formation.

We present results of the study of peculiar motions of 57 clusters and groups of galaxies in the regions of the Corona Borealis (CrB), Bootes (Boo), Z5029/A1424, A1190, A1750/A1809 superclusters of galaxies and 20 galaxy clusters located beyond massive structures ($0.05

We study the variations of the properties of groups of galaxies with dynamical masses of 1013 M ⊙ 1 for the LF of the Hercules and Leo superclusters of galaxies.

In this paper we study the relations between the main characteristics of groups and clusters of galaxies using the archival data of the SDSS and 2MASX catalogs. We have developed and implemented a new method of determining the size of galaxy systems and their effective radius which contains half of the galaxies and not half the luminosity, since the luminosity of the brightest galaxy in a group can account for over 50% of the total luminosity of the group. The derived parameters (log L K , logR e , and log σ 200) for 94 systems of galaxies (0.0038 < z < 0.09) determine the Fundamental Plane (FP), which, with a scatter of 0.15, is similar in form to the FP of galaxy clusters obtained by Schaeffer et al. (1993) and D’Onofrio et al. (2013) with other methods and for different bands. We show that the FP in the near-infrared region (NIR) for 94 galaxy systems has the form of L K ∝ $$R_e^{0.70 \pm {{0.13}_\sigma }1.34 \pm 0.13}$$ , whereas in x-rays it has the form of—L X ∝ $$R_e^{1.15 \pm {{0.39}_\sigma }2.56 \pm 0.40}$$ . The form of the FP for groups and clusters is consistent with the FP for early-type galaxies determined in the same way. The form of the FP for galaxy systems deviates from the shape that one would expect from virial predictions. Adding the mass-to-light ratio as a fourth independent parameter has little effect on this deviation, but decreases the scatter of the FP for a sample of rich galaxy clusters by 12%.

We report the results of measurement and comparison of masses for a sample of 29 groups and clusters of galaxies (z < 0.1). We use the SDSSDR7 archive data to determine dynamical masses from the one-dimensional dispersion of line-of-sight velocities for virialized regions of radii R200 and Re. Our method for determination of effective radii of galaxy systems fromthe cumulative distribution of the number of galaxies depending on squared clustercentric distance allowed us to estimate masses M1/2 (within Re), which are related to the masses contained inside R200: M200 ~ 1.65M1/2. A comparison of the inferred dynamic masses and the hydrostatic masses determined from the radiation of hot gas in galaxy groups and clusters (based on published data) led us to conclude that the inferred masses for the main sample of 21 groups and clusters agree to within 12%. These systems also obey the relation MX,200 ~ 1.65M1/2. For the remaining eight systems, which are mostly located in the Hercules supercluster, the discrepancy between the hydrostatic and the dynamic masses amounts to 2σ. This discrepancy is most likely due to the incompleteness of the formation processes of these clusters via hierarchical merger in the region of the rich Hercules supercluster.

In order to extend the relationship between the infrared luminosity of groups and clusters of galaxies and their dynamic mass to the 1–5 × 1013 M ⊙ mass region, we selected from the study of Ramella et al. (2004) certain galaxy groups in the region of 0.012 < z < 0.027. Based on the archive data from the SDSS, NED, and 2MASX, for these 34 galaxy groups we determined the dynamic and photometric characteristics. Overall, the sample has the following median characteristics: z = 0.0226, M 200 = 0.58 × 1014 M ⊙, L K = 1.26 × 1012 L ⊙, and N(M K < −21m) = 22. Having this sample added to the earlier prepared sample of 148 groups and clusters of galaxies, we found the following relationships between the dynamic mass M 200, infrared (IR) luminosity, and the number of galaxies within the R 200 radius: L K (M K < −21m) ∝ M 0.77, N(M K < −21m) ∝ M 0.82, and M/L K ∝ L K 0.22 . Practically all the members of the studied sample show a good agreement between the dynamic mass of groups M 200 and IR luminosity of galaxies, and eventually their stellar mass (only the group MKW12 deviates more than 2σ in all the dependencies).

We present the results of our study of the peculiar motions for 41 galaxy clusters and groups in the regions of the Hercules and Leo superclusters (0.027 < z < 0.045). For this purpose, based on SDSS (Data Release 8) data, we compiled a sample of early-type galaxies in the investigated clusters and groups, constructed their fundamental planes (FPs), and determined independent distances and peculiar velocities. The Hubble law between the radial velocities galaxy clusters and the distances derived from the FPs holds for the rich Hercules supercluster as a whole. At the same time, however, significant peculiar motions along the line of sight with rms deviations of 736 ± 50 and 584 ± 50 km s−1 are observed within this supercluster and in its immediate neighborhood. In the poor Leo supercluster, the rms deviation is also large, 625 ± 70 km s−1. Its Hubble diagram exhibits the approach of galaxy clusters and groups along the line of sight relative to the most massive cluster A1185. In the immediate neighborhood of the Leo supercluster (virtually in its field), the rms deviation of the peculiar velocities is minimal, 287 ± 60 km s−1.

We present results of the study of peculiar motions of 57 clusters and groups of galaxies in the regions of the Corona Borealis (CrB), Bootes (Boo), Z5029/A1424, A1190, A1750/A1809 superclusters of galaxies and the galaxy clusters located beyond massive structures (0.05 < z < 0.10). Using the SDSS (Data Release 8) data, a sample of early-type galaxies was compiled in the systems under study, their fundamental planes were built, and relative distances and peculiar velocities were determined. Within the galaxy superclusters, significant peculiar motions along the line of sight are observed with rms deviations of 652 ± 50 kms−1—in CrB, 757 ± 70 kms−1—in Boo. In the most massive A2065 cluster in the CrB supercluster, no peculiar velocity was found. Peculiar motions of the other galaxy clusters can be caused by their gravitational interaction both with A2065 and with the A2142 supercluster. It has been found that there are two superclusters projected onto each other in the region of the Bootes supercluster with a radial velocity difference of about 4000 kms−1. In the Z 5029/A1424 supercluster near the rich Z5029 cluster, the most considerable peculiar motions with a rms deviations of 1366 ± 170 kms−1 are observed. The rms deviations of peculiar velocities of 20 clusters that do not belong to large-scale structures is equal to 0 ± 20 kms−1. The whole sample of the clusters under study has the mean peculiar velocity equal to 83 ± 130 kms−1 relative to the cosmic microwave background.

We report the results of the study of red-sequence (RS) galaxies in 47 galaxy clusters (0.023 < z < 0.047) located in different environments: in the superclusters Hercules and Leo, and in the field, based on the SDSS catalog data. In the interval, the number of bright RS dwarf galaxies in galaxy clusters increaseswith the X-ray luminosity of the cluster as logN ∝ log 0.64 . The dwarf-to-giant ratio (DGR) does not depend on the surroundings, mass, or richness of the cluster. This ratio is seen to increase for galaxy clusters with log L X > 43.5 erg/s or σ > 520 km/s. The compositeDGR of galaxy clusters, determined both from the membership in different structures and the X-ray luminosity along the radius R 200, is minimum in the central regions of the clusters (about 0.6 ± 0.06), reaches a maximum within 0.3–0.9R 200 (about 0.9 ± 0.10), and decreases approximately to 0.7 ± 0.03 upon reaching the radius 1.4 R 200.

We investigated the properties of galaxy clusters in the region of the Hercules supercluster using observational data from the SDSS and 2MASS catalogs and the NED. We have selected 13 galaxy clusters with a total dynamical mass of 4.82 × 1015 M ⊙ in a 100 × 45 Mpc supercluster region in the plane of the sky (0.030 < z < 0.041). In addition, our sample includes eight clusters from the immediate neighborhoods of the superclusters and ten field clusters at the same z. The derived properties of the rich Hercules supercluster are shown in comparison with the data for the poor Leo supercluster. The main parameters of the virialized galaxy cluster regions in the near infrared (K s ) for the Hercules supercluster differ from those for the Leo supercluster: the number of galaxies and the total luminosity (to a limiting magnitude of −21 · 5) increase with cluster mass (L K,200 ∝ M 200 0.91±0.07 and N 200 ∝ M 200 0.94±0.07 ), but the dependences are steeper by 0.28 and 0.22. In the virialized cluster regions, the fraction of early-type galaxies selected by the bulge contribution, concentration index, and u t= r color is, on average, 66% (60% in Leo, 70% in the field) among the galaxies brighter than −23 · 3 and 54% (51% in Leo, 61% in the field) among the galaxies brighter than −22 · 3. The fraction of early-type galaxies in the superclusters does not change with galaxy cluster mass and luminosity. The composite luminosity function of the rich Hercules supercluster is described by a Schechter function and does not differ from the luminosity function of the poor Leo supercluster for the luminosity interval [−26 m , −21 · 5] but differs from the field luminosity function at the same z determined from ten galaxy clusters.

We report the results of study of the A1569 cluster (12h36m.3, +16°35′) and the neighboring A1589 cluster (12h41m.3, +18°34′), making up a pair (a supercluster) with a projected size of about 10Mpc. This study is done within the framework of our program for investigating the galaxy clusters with bimodal velocity distributions (i.e., clusters where the velocities of subsystems differ by more than Δcz ∼ 3000 km/s). In the A1569 cluster we have identified two subsystems: A1569A (cz = 20613 km/s) and A1569B (cz = 23783 km/s). These subsystems have the line-of-sight velocity dispersions of 484 km/s and 493 km/s, and dynamic masses within the R200 radius equal to 1.8 × 1014 and 2.0 × 1014M⊙, respectively. We directly estimate the distances to these subsystems using three methods applied to earlytype galaxies: the Kormendy relation, photometric plane, and fundamental plane. To this end, we use the results of our observations made with the 1-m telescope of the SAO RAS and the data adopted from the SDSS DR7 catalog. We found that A1569 consists of two independent clusters. The A1569B cluster is located at the Hubble distance corresponding to its radial velocity. The A1569A cluster has a peculiar velocity of −1290 ± 630 km/s, which can be explained by the effect of the more massive A1589 cluster (with a mass of 7.9 × 1014M⊙) and of the supercluster where it resides. In all the four bimodal clusters that we studied within the framework of our program, A1035, A1775, A1831, and A1569, the subsystems are independent clusters lying close to the Hubble relation between redshift and distance.

We analyze the properties of galaxy clusters in the region of the Leo supercluster using observational data from the SDSS and 2MASS catalogs. We have selected 14 galaxy clusters with a total dynamical mass of 1.77 × 1015 M ⊙ in the supercluster region 130 by 60 Mpc in the plane of the sky (z ≃ 0.037). The composite luminosity function of the supercluster is described by a Schechter function with parameters that, within the error limits, correspond to field galaxies and does not differ from the luminosity function of the richer Ursa Major (UMa) supercluster for the same luminosity range (the bright end). The luminosity functions of early-type and late-type galaxies in Leo at the faint end are characterized by a sharp decrease (α = −0.60±0.08) and a steep increase (α = −1.44± 0.10) in the number of galaxies, respectively. In the virialized cluster regions, the fraction of early-type galaxies selected by the u-r color, bulge contribution, and concentration index among the galaxies brighter than M * + 1 is, on average, 62%. This fraction is smaller than that in the UMa supercluster at a 2–3σ level. The near-infrared luminosities of galaxy clusters down to a fixed absolute magnitude correlate with their masses almost in the same way as for other samples of galaxy clusters (L 200,K ∝ M 200 0.63±0.11 )).

We study the A1831 cluster within the framework of our program of the investigation of galaxy clusters with bimodal velocity distributions (i.e., clusters where the velocities of subsystems differ by more than Δ cz ∼ 3000 km/s).We identify two subsystems in this cluster: A1831A (cz = 18970 km/s) and A1831B (cz = 22629 km/s) and directly estimate the distances to these subsystems using three methods applied to early-type galaxies: the Kormendy relation, the photometric plane, and the fundamental plane. To this end, we use the results of our observations made with the 1-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences and the data adopted from the SDSS DR6 catalog. We confirmed at a 99% confidence level that (1) the two subsystems are located at different distances, which are close to their Hubble distances, and (2) the two subsystems are located behind one another along the line of sight and are not gravitationally bound to each other. Both clusters have a complex internal structure, which makes it difficult to determine their dynamical parameters. Our estimates for the velocity dispersions and masses of the two clusters: 480 km/s and 1.9 × 1014 M ⊙ for A1831A, 952 km/s and 1.4 × 1015 M ⊙ for A1831B should be views as upper limits. At least three spatially and kinematically distinct groups of galaxies can be identified in the foreground cluster A1831A, and this fact is indicative of its incomplete dynamical relaxation. Neither can we rule out the possibility of a random projection. The estimate of the mass of the main cluster A1831B based on the dispersion of the line-of-sight velocities of galaxies is two-to-three times greater than the independent mass estimates based on the total K-band luminosity, temperature, and luminosity of the X-ray gas of the cluster. This fact, combined with the peculiarities of its kinematical structure, leads us to conclude that the cluster is in a dynamically active state: galaxies and groups of galaxies with large line-of-sight velocities relative to the center of the cluster accrete onto the virialized nucleus of the cluster (possibly, along the filament directed close to the line of sight).

We present the results of optical identification of 248 interplanetary scintillating (IPS) radio sources from the Pushchino Survey (PS) in the area of 0.11 sr with the center at $\alpha =10^{\rm h}28^{\rm m}, \delta =+41^\circ$. All 260 counterparts of IPS radio sources from the 7C and FIRST catalogues, which had been found in Paper I, were considered. We used USNO– B 1.0 catalogue (limiting magnitude $m_R\approx 21$) for the optical identification and searched the literature to find optical data for fainter objects. Photometric and spectroscopic observations were conducted on the 1 m and 6 m telescopes of SAO RAS. Optical magnitudes or deep limits for 22 objects and redshifts for 26 ones have been obtained. In total, we collected optical data for 116 (68 with redshift) counterparts of the PS radio sources. For the subsample of the PS quasars (41 objects) the redshift distribution was compared to those of several other samples of quasars (BRL, 3CRR, MQS, B3–VLA, 7CRS I–III and PKS 0.25 Jy) which have complete or nearly complete redshift information.

Interplanetary scintillating (IPS) radio sources from the Pushchino Survey (PS) in the area of 0.11 sr have been cross-identified with objects from the 7C and FIRST catalogues. We have obtained improved positions of IPS radio sources, which are necessary for their optical identification. The data on sizes and morphology provided by the FIRST catalogue have shown that more than 50% of IPS radio sources are single and compact (

We present the results of a study of streaming motion of galaxy clusters around the Giant Void ($\alpha \approx 13^{\rm h}, \delta \approx 40^\circ, z \approx 0.11$ and a diameter of 300 Mpc) in the distribution of rich Abell clusters. We used the Kormendy relation as a distance indicator taking into account galaxy luminosities. Observations were carried out in Kron–Cousins R c system on the 6 m and 1 m telescopes of SAO RAS. For 17 clusters in a spherical shell of 50 Mpc in thickness centered on the void no significant diverging motion (expected to be generated by the mass deficit in the void) has been detected. This implies that cosmological models with low $\Omega_{\rm m}$ are preferred. To explain small mass underdensity inside the Giant Void, a mechanism of void formation with strong biasing is required.

Kormendy’s relation (μe-logR e) is used to investigate the structure of the compact Ursa Major supercluster of galaxies (11h30m+55°, cz=18 000 km s−1); this relation allows the distances of early-type galaxies to be estimated. The relative distances of 13 clusters in the supercluster and their peculiar velocities are determined with a mean statistical accuracy of 6%. In general, the supercluster obeys the Hubble relation between radial velocity and distance. However, there is reason to suggest that the supercluster consists of two subsystems with mean radial velocities of 16 200 and 19 700 km s−1. For a velocity dispersion in the subsystems of ∼1100 km s−1, the fact that each of them is gravitationally bound is not ruled out.

Catalogs of bright galaxies in the central regions of 11 clusters in the Ursa Major supercluster are presented. Absolute and relative coordinates and total B and R magnitudes are given for each galaxy. Plates taken with the 2-m Tautenburg Observatory telescope and CCD images obtained with the 6-m and 1-m SAO telescopes are used. The luminosity functions (LFs) for galaxies in the cluster nuclei (3 Mpc×3 Mpc) and the composite LF for the supercluster are constructed. The composite LF is well fitted by a Schechter function with $$M_B^ * = - 20\mathop .\limits^m 91$$ , α=−1.02 and with $$M_R^ * = - 22\mathop .\limits^m 39$$ , α=−1.06. A comparison with the LFs of field galaxies and of various samples of clusters and superclusters shows that the Ursa Major supercluster have LF parameters characteristic of the field and, thus, differ from those of the Corona Borealis supercluster, which is apparently at a later stage of dynamical evolution.

We analyze the properties of the clusters of galaxies in the region of the Ursa Major (UMa) supercluster using observational data from SDSS and 2MASS catalogs. The region studied includes a supercluster (with a galaxy and cluster overdensity of 3 and 15, respectively) and field clusters inside the 150 Mpc diameter surrounding region. The total dynamical mass of 10 clusters of galaxies in UMa is equal to 2.25 10^15 M_sun, and the mass of 11 clusters of galaxies in the UMa neighborhood is equal to 1.70 10^15 M_sun. The fraction of early-type galaxies brighter than M_K*+1 in the virialized regions of clusters is, on the average, equal to 70%, and it is virtually independent on the mass of the cluster. The fraction of these galaxies and their average photometric parameters are almost the same both for UMa clusters and for the clusters located in its surroundings. Parameters of the clusters of galaxies, such as infrared luminosities up to a fixed magnitude, the mass-to-luminosity ratio, and the number of galaxies have almost the same correlations with the cluster mass as in other samples of galaxies clusters. However, the scatter of these parameters for UMa member clusters is twice smaller than the corresponding scatter for field clusters, possibly, due to the common origin of UMa clusters and synchronized dynamical evolution of clusters in the supercluster., 32 pages, 3 tables, 31 figures

We analyze the structure of the cluster of galaxies Abell 1775 (13h42m, +26d22', cz ~ 21000 km/s), which exhibits a bimodal distribution of radial velocities of the containing galaxies. The difference of the subcluster radial velocities is \Delta V\approx 2900 km/s. We use the results of our photometric observations made with the 1-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences and the spectroscopic and photometric data from the SDSS DR6 catalog to determine independent distances to the subclusters via three different methods: the Kormendy relation, photometric plane, and fundamental plane. We find that the A1775 cluster consists of two independent clusters, A1775A (cz=19664 km/s) and A1775B (cz=22576 km/s), each located at its own Hubble distance and having small peculiar velocities. Given the velocity dispersions of 324 km/s and 581 km/s and the dynamic masses within the R_200 radius equal to 0.6 10^14 and 3.3 10^14 M_sun, the A1775A and A1775B clusters have the K-band luminosity-to-mass ratios of 29 and 61, respectively. A radio galaxy with an extended tail belongs to the A1775B cluster., Comment: 14 pages, 3 tables, 5 figures

We have investigated the peculiar motions of clusters of galaxies in the Ursa Major (UMa) supercluster and its neighborhood. Based on SDSS (Sloan Digital Sky Survey) data, we have compiled a sample of early-type galaxies and used their fundamental plane to determine the cluster distances and peculiar velocities. The samples of early-type galaxies in the central regions (within R_200) of 12 UMa clusters of galaxies, in three main subsystems of the supercluster -- the filamentary structures connecting the clusters, and in nine clusters from the nearest UMa neighborhood have similar parameters. The fairly high overdensity (3 by the galaxy number and 15 by the cluster number) suggests that the supercluster as a whole is gravitationally bound, while no significant peculiar motions have been found: the peculiar velocities do not exceed the measurement errors by more than a factor of 1.5-2. The mean random peculiar velocities of clusters and the systematic deviations from the overall Hubble expansion in the supercluster are consistent with theoretical estimates. For the possible approach of the three UMa subsystems to be confirmed, the measurement accuracy must be increased by a factor of 2-3., Comment: 21 pages, 4 tables, 7 figures

We study the infrared (K_s band) properties of clusters of galaxies in the Ursa Major supercluster using data from 2MASS (Two-Micron All-Sky Survey) and SDSS (Sloan Digital Sky Survey). We identified three large filaments with mean redshifts of z = 0.051, 0.060, and 0.071. All clusters of the supercluster are located in these filaments. We determined the total K_s-band luminosities and masses for 11 clusters of galaxies within comparable physical regions (within a radius R_200 close to the virial radius) using a homogeneous method. We constructed a combined luminosity function for the supercluster in this region, which can be described by the Schechter function with the following parameters: M*_K = -24^m.50 and \alpha = -0.98. The infrared luminosities of the clusters of galaxies correlate with their masses; the M/L_K ratios of the systems increase with their masses (luminosities), with most of the Ursa Major clusters of galaxies (particularly the richer ones) closely following the relations derived previously for a large sample of clusters and groups of galaxies. The total mass-to-infrared-luminosity ratio is 52 M_{\odot}/L_{\odot} for six Abell clusters and 49 M_{\odot}/L_{\odot} for all of the clusters, except Anon2., Comment: 16 pages, 5 figures