No abstract

The morphological content of Markarian galaxies (MG) in groups and in single galaxies is examined. It is found that MG do not conform to the long established rule that the relative number of elliptical and lenticular galaxies in groups is higher than in single galaxies.The relationship of high surface brightness Arakelian galaxies to their environment was studied in Ref. 1. In particular, it was found that these galaxies do not conform to the well established rule according to which elliptical and lenticular galaxies are encountered more often in groups of galaxies than among single galaxies. In this note we obtain analogous statistics for Markarian galaxies with an ultraviolet continuum.We use the same sample [2] as in Ref. 1 for the list of groups of galaxies.Here we discuss the morphological distribution of Markarian galaxies which are members of groups and those which are single. Since the number of Markarian galaxies of known morphological types in the CfA2 catalog is small, we divide the galaxies into two parts with respect to their morphological type: elliptical (elliptical and lenticular) and spiral.In order to reduce the effect on the results owing to differences in the distributions of the visible stellar magnitudes, as well to differences in the mean distances of the samples, we impose limits on the stellar magnitudes (m = 13-15) and radial velocities (V = 2000-8000 km/s) of the samples of galaxies to be compared.

The relationship of high surface brightness Arakelian galaxies (ArG) to their environment is studied. This is done using the groups identified by the authors on the basis of the CfA2 red shift survey. Of the 15577 galaxies in the sample, 172 (1.104%) have a high surface brightness. The corresponding percentage for the galaxies with 0 . 15 0 . 13 ≤ < m is 2.05. The following results are obtained: (a) On going from single to poor groups and on to more populated groups, the frequency of occurrence of ArG does not vary. (b) Groups of galaxies containing ArG do not differ on the average from groups which do not contain such galaxies in terms of their dynamic characteristics, such as the dispersion in radial velocity, size, and total luminosity, or their morphological content. (c) ArG do not follow the regular pattern according to whichelliptical and lenticular galaxies are more often encountered in groups of galaxies than among single galaxies, i.e., it seems that the frequency of occurrence of elliptical and lenticular ArG in groups is the same as in single galaxies. (d) The surface brightnesses, diameters, and luminosities of ArG in groups of galaxies are greater than those of single ArG. This shows up especially strongly in spiral ArG.

The Schmidt method for constructing the luminosity function of galaxies is generalized to include the dependence of the density of galaxies on distance in the near universe. The logarithmic luminosity function (LLF) of the field galaxies as a function of morphological type is constructed. It is found that the LLF for all the galaxies, as well as separately for elliptical and lenticular galaxies, can be represented as a Schechter function within a narrow range of absolute magnitudes. The LLF for spiral galaxies is a Schechter function over a rather wide range of absolute magnitudes,. The parameter M * varies little over the spiral galaxies. The parameter α in the Schechter function decreases on going from early to later spirals. On going from elliptical to lenticular galaxies, from early spiral galaxies and onward to later spiral galaxies, a decrease in the average luminosity of the galaxies is observed in the bright end, 8 17 23 . M − ≤ ≤ − . The completeness and average density of the samples are estimated for galaxies of different morphological types. The average number density of all the galaxies within the range 13 23 − ≤ ≤ − M is 0.126 Mpc -3 .

This article proposes a method for constructing the luminosity function of galaxies, which gives a result that is consistent with other methods, is as accurate as other methods, and is simple. Using this method, we constructed the luminosity function of Arakelian galaxies with different morphological types in different environments, included in the CfA2 catalog. The proposed method of identifying groups of galaxies is physically grounded and simple. It was found that both the bright and weak parts of the normalized luminosity function of Arakelian galaxies are higher than the bright and weak parts of the similar function of the total sample CfA2. A similar phenomenon is observed separately for members of groups, as well as for single galaxies. This also applies to small groups with 2 or 3 galaxies, and more populated groups. Spiral galaxies obey these laws. For elliptical galaxies, the picture is not very clear (due to the small number of well-known elliptical Arakelian galaxies). The spatial density of the number of ArG in the M≤-17 range is 0.00068 ± 0.00005 Mpc^-3, which corresponds to 2.7% of the entire sample in this range (for CfA2 (M≤-17) = 0.0254 ± 0.0002 Mpc^-3).