Galaxies infalling into groups: filaments versus isotropic infall

COENDA, V.; MURIEL, H.; MARTINEZ, H.J.

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2016 vol. 455 p. 127 - 135

0035-8711

We perform a comparative analysis of the properties of galaxies infalling intogroups classifying them accordingly to whether they are: falling along filamentary structures; or they are falling isotropically. For this purpose, we identify filamentary structures connecting massive groups of galaxies in the SDSS. We perform a comparative analysis of some properties of galaxies in filaments, in the isotropic infall region, in the field, and in groups.We study the luminosity functions (LF) and the dependence of the specific star formation rate (SSFR) on stellar mass, galaxy type, and projected distance to the groupsthat define the filaments. We find that the LF of galaxies in filaments and in the isotropic infalling regionare basically indistinguishable between them, with the possible exception of late-typegalaxies. On the other hard, regardless of galaxy type, their LFs are clearly different from that of field or group galaxies. Both of them have characteristic absolute magnitudes and faint end slopes in between the field and group values.More significant differences between galaxies in filaments and in the isotropicinfall region are observed when we analyse the SSFR. We find that galaxies in filaments have a systematically higher fraction of galaxies with low SSFR as a function of both, stellar mass and distance to the groups, indicatinga stronger quenching of the star formation in the filaments compared to both,the isotropic infalling region, and the field.Our results suggest that some physical mechanisms that determine the differences observed between field galaxies and galaxies in systems, affect galaxies even when they are not yet within the systems.