The dynamical state of galaxy groups and their luminosity content

MARTÍNEZ, H. J.; ZANDIVAREZ, A.

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LETTERS

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2012 p. 24 - 28

We analyse the dependence of the luminosity function (LF) of galaxies in groups on group dynamical state. We use the Gaussianity of the velocity distribution of galaxy members as a measurement of the dynamical equilibrium of groups identified in the Sloan Digital Sky Survey Data Release 7 by Zandivarez & Martínez. We apply the Anderson-Darling goodness-of-fit test to distinguish between groups according to whether they have Gaussian or non-Gaussian velocity distributions, i.e. whether they are relaxed or not. For these two subsamples, we compute the 0.1r-band LF as a function of group virial mass and group total luminosity. For massive groups, ?, we find statistically significant differences between the LF of the two subsamples: the LFs of groups that have Gaussian velocity distributions have a brighter characteristic absolute magnitude (?0.3 mag) and a steeper faint-end slope (?0.25). We detect a similar effect when comparing the LF of bright [?] Gaussian and non-Gaussian groups. Our results indicate that, for massive/luminous groups, the dynamical state of the system is directly related to the luminosity of its galaxy members.