The Atomic Hydrogen Content of Galaxies as a function of Group-Centric Radius
Résumé
We apply a spectral stacking technique to Westerbork Synthesis Radio Telescope observations to measure the neutral atomic hydrogen content (H) of nearby galaxies in and around galaxy groups at < 0.11. Our sample includes 577 optically-selected galaxies (120 isolated galaxies and 457 satellites) covering stellar masses between 10 10 and 10 11.5 M ⊙ , cross-matched with Yang's group catalogue, with angular and redshift positions from the Sloan Digital Sky Survey. We find that the satellites in the centres of groups have lower H masses at fixed stellar mass and morphology (characterised by the inverse concentration index) relative to those at larger radii. These trends persist for satellites in both high-mass (halo > 10 13.5 ℎ −1 M ⊙) and lowmass (halo 10 13.5 ℎ −1 M ⊙) groups, but disappear if we only consider group members in low local density (Σ < 5 gal/Mpc −2) environments. Similar trends are found for the specific star formation rate. Interestingly, we find that the radial trends of decreasing H mass with decreasing group-centric radius extend beyond the group virial radius, as isolated galaxies close to larger groups lack H compared with those located more than ∼3.0 180 away from the center of their nearest group. We also measure these trends in the late-type subsample and obtain similar results. Our results suggest that the H reservoir of galaxies can be affected before galaxies become group satellites, indicating the existence of pre-processing in the infalling isolated galaxies.
Domaines
Physique [physics]
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