Affiliation: NISER
Conference ID : ASI2022_608
Title : The Distribution of Neutral Hydrogen in the Local Universe
Authors : Nishikanta Khandai, Saili Dutta, Sandeep Rana, Biprateep Dey
Abstract Type: Invited
Abstract Category : Plenary
Abstract : We use a survey volume common to the SDSS and ALFALFA surveys to constrain the conditional neutral hydrogen (HI) mass and velocity-width functions, conditioned on optical color and/or magnitude. This allows us to further constrain the distribution function of the cosmic HI density in the color-magnitude plane of galaxies. We find that the distribution has a long tail towards faint blue galaxies and luminous red galaxies. About 10% of the HI budget is associated with low surface brightness galaxies whereas 18% is locked up in the red population of galaxies. We use these abundances and recent stacking results from the ALFALFA survey to constrain the halo mass function of HI-selected galaxies. The transition halo mass scale in the halo mass - HI mass relation is smaller by ~ 1.4 dex to that of the halo mass - stellar mass relation, suggesting that baryonic processes like heating and feedback in larger mass halos suppress HI gas on a shorter time scale compared to star formation. We show that our observationally calibrated HI halo model reproduces the clustering of HI selected galaxies.