Galaxies infalling into groups: filaments vs. isotropic infall

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

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2016 vol. 455

0035-8711

We perform a comparative analysis of the properties of galaxies infalling into groups classifying them accordingly to whether they are: falling along filamentary structures; or they arefalling isotropically. For this purpose, we identify filamentary structures connecting massivegroups of galaxies in the SDSS. We perform a comparative analysis of some properties ofgalaxies in filaments, in the isotropic infall region, in the field, and in groups. We study theluminosity functions (LF) and the dependence of the specific star formation rate (SSFR) onstellar mass, galaxy type, and projected distance to the groups that define the filaments. Wefind that the LF of galaxies in filaments and in the isotropic infalling region are basically indistinguishable between them, with the possible exception of late-type galaxies. On the otherhard, regardless of galaxy type, their LFs are clearly dierent from that of field or groupgalaxies. Both of them have characteristic absolute magnitudes and faint end slopes in between the field and group values. More significant dierences between galaxies in filamentsand in the isotropic infall 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 functionof both, stellar mass and distance to the groups, indicating a stronger quenching of the starformation in the filaments compared to both, the isotropic infalling region, and the field. Ourresults suggest that some physical mechanisms that determine the dierences observed between field galaxies and galaxies in systems, aect galaxies even when they are not yet withinthe systems.