SIMBAD references

We use spectral stacking to measure the contribution of galaxies of different masses and indifferent hierarchies to the cosmic atomic hydrogen (HI) mass density in the local Universe.Our sample includes 1793 galaxies atz<0.11 observed with the Westerbork SynthesisRadio Telescope, for which Sloan Digital Sky Survey spectroscopy and hierarchy informationare also available. We find a cosmic HImass density ofHI=(3.99±0.54)x10-4h-170at<z> =0.065. For the central and satellite galaxies, we obtainHIof (3.51±0.49)x10-4h-170and (0.90±0.16)x10-4h-170, respectively. We show that galaxies above and below stellarmasses of∼109.3Mcontribute in roughly equal measure to the global value ofHI. Whileconsistent with estimates based on targeted HIsurveys, our results are in tension with previoustheoretical work. We show that these differences are, at least partly, due to the empirical recipeused to set the partition between atomic and molecular hydrogen in semi-analytical models.Moreover, comparing our measurements with the cosmological semi-analytic models of galaxyformation SHARKand GALFORM reveals gradual stripping of gas via ram pressure worksbetter to fully reproduce the properties of satellite galaxies in our sample than strangulation.Our findings highlight the power of this approach in constraining theoretical models andconfirm the non-negligible contribution of massive galaxies to the HImass budget of the localUniverse.