Shakhbazian compact galaxy groups

Abstract

Abstract. We present the results of a detailed spectroscopic and photometric study of four Shakhbazian compact groups: ShCG 8, ShCG 14, ShCG 19, and ShCG 22. We determined the redshifts of member galaxies and radial velocity dispersions of groups. We also studied the distribution of the surface brightness of member galaxies in R and determined their morphological types. The profiles of the surface brightness versus semi-major axis, the curves of isophotal twisting, and Fourier parameter a 4 are constructed. We found that some members of groups are in the process of interaction. We determined physical parameters of groups: virial masses, luminosities, mass-to-luminosity ratios, and the crossing times. On the basis of the results obtained in this and our previous works, the general properties of 22 ShCGs are discussed.Key words. galaxies: clusters: general -galaxies: distances and redshifts -galaxies: interactions -galaxies: generalgalaxies: kinematics and dynamics -galaxies: photometry IntroductionIn 1995 we commenced a spectroscopic and detailed photometric study of Shakhbazian compact groups (ShCGs). The list of ShCGs contains 377 groups (Shakhbazian 1973;Petrosian 1974Petrosian , 1978Baier et al. 1974;Baier & Tiersch 1975, 1976a, 1976b, 1978, 1979. ShCGs were found by an eye inspection of the POSS prints. They were selected as dense groups of mainly red galaxies, the images of many of which were often hard to distinguish from those of stars. Through follow-up spectral observations (Tiersch et al. 2002, hereafter Paper I;Tovmassian et al. 2003a, hereafter Paper II, 2003b, hereafter Paper III, 2004a, hereafter Paper IV, 2004b, hereafter Paper V) it was found that some objects in the area of groups which were assumed in original papers to be stars, are in reality galaxies. On the other hand, only a Figures 1 and 3-10 are only available in electronic form at http://www.edpsciences.org few assumed members of ShCGs turned out to be stars. Hence, the great majority of the assumed members of these groups are galaxies.Many ShCGs, like ShCG 19 and ShCG 38 (Fig. 1), are very dense formations. Probably due to the compactness of images of the member galaxies, which on the POSS prints are almost indistinguishable from those of stars, these two groups and also some others were missed in other compact group lists, e.g. HCG list (1982). ShCGs generally consist of up to 15 members, while the distances between member galaxies are typically 3−5 times their diameters. The space density of many of ShCGs reaches about 10 4 −10 5 galaxies per Mpc 3 . The groups have a "cigar"-like, prolate spheroid configuration (Oleak et al. 1995). Numerical N-body simulations have showen that compact groups should undergo fast dynamical evolution, which will result in coalescence of member galaxies to one giant elliptical galaxy (Barnes 1985(Barnes , 1989Mamon 1986;Bode et al. 1993). It means that processes of dynamical Article published by EDP Sciences and available at http://www.edpsciences.org/aa or http://dx

EXPLORING HOT GAS AT JUNCTIONS OF GALAXY FILAMENTS WITHSUZAKU

“…(A color version of this figure is available in the online journal.) S0 galaxy in the group ShCG 188, are observed, and one of the halos is directed toward another as shown in Tovmassian et al (2005), which suggests that the group is experiencing an ongoing major merger event because a single massive galaxy can be the responsible perturber in groups. It is also suggested that one more member galaxy is involved in the interaction because the bulge of the galaxy is shifted toward the interacting galaxies.…”

“…The filaments run almost in the same plane perpendicular to the line of sight. Filament Junction 2 (FJ2) has an optically bright galaxy (SDSS J095701.27+261027.7) at z ∼ 0.082 located in the center of Shakhbazian compact group (ShCG) 188 at z = 0.080 (Tovmassian et al 2005) and two filaments run perpendicular to and along the line of sight, respectively. Filament Junctions 3, 4, and 5 (FJ3, FJ4, and FJ5) are located at several-filament intersections.…”

Redshifts of 19 Shakhbazian compact groups of galaxies

“…CGs, the list of which was compiled recently by Tovmassian, Torres-Papaqui, and Tiersch [46], who showed that 28% out of 98 ShCGs with known redshifts of their members are dense condensations in clusters of galaxies, 28% are condensations in LGs, and 26% are isolated compact groups. At projected distances of up to 1 Mpc in the environment of the latter there are no galaxies with redshifts differing from the mean redshift of the corresponding group by less than 1000 km s -1 .…”

Shakbazian Compact Groups: Mass‐to‐light ratios and mass distribution models: I. ShCG 362 and ShCG 166

“…Thus their study is of great interest in the context of dynamical evolution and interaction of galaxies (see Tovmassian et al 2005, hereafter T05; and references therein for a review).…”