Galaxy groups in the 2dF Redshift Survey: galaxy spectral type segregation in groups

DOMINGUEZ, M.; ZANDIVAREZ, A.; HECTOR JULIAN MARTINEZ; MERCHAN, M. E.; HERNAN MURIEL; LAMBAS, D. G.

Buenos Aires

Congreso; Reunion Anual de la Asociacion Argentina de Astronomia; 2002

Asociacion Argentina de Astronomia

Galaxies with different spectral types in groups is analysed as a function of projected local galaxy density and the group-centric distance. The group sample was taken from the 2dF Group Galaxy Catalogue constructed by Merchán & Zandivarez. Our group sample was constrained to have a homogeneous virial mass distribution with redshift. Galaxies belonging to this group sample were selected in order to minimize possible biases such as preferential selection of high luminosity objects. We find a clear distinction between high virial mass groups (MV≈ 1013.5 Mȯ) and the less massive ones. While the massive groups show a significant dependence of the relative fraction of low star formation galaxies on local galaxy density and group-centric radius, groups with lower masses show no significant trends. We also cross-correlate our group subsample with the previously identified clusters finding that this sample shows a very similar behaviour as observed in the high virial mass group subsample.