We introduce a new photometric estimator of the H i mass fraction () in local galaxies, which is a linear combination of four parameters: stellar mass, stellar surface mass density, NUV−r colour and g−i colour gradient. It is calibrated using samples of nearby galaxies (0.025 < z < 0.05) with H i line detections from the GALEX Arecibo SDSS Survey (GASS) and Arecibo Legacy Fast ALFA (ALFALFA) surveys, and it is demonstrated to provide unbiased estimates even for H i-rich galaxies. We apply this estimator to a sample of ∼24 000 galaxies from the Sloan Digital Sky Survey (SDSS)/Data Release 7 (DR7) in the same redshift range. We then bin these galaxies by stellar mass and H i mass fraction and compute projected two-point cross-correlation functions with respect to a reference galaxy sample. Results are compared with predictions from current semi-analytic models of galaxy formation. The agreement is good for galaxies with stellar masses larger than 1010 M⊙, but not for lower mass systems.
We then extend the analysis by studying the bias in the clustering of H i-poor or H i-rich galaxies with respect to galaxies with normal H i content on scales between 100 kpc and ∼5 Mpc. For the H i-deficient population, the strongest bias effects arise when the H i deficiency is defined in comparison to galaxies of the same stellar mass and size. This is not reproduced by the semi-analytic models, where the quenching of star formation in satellites occurs by ‘starvation’ and does not depend on their internal structure. H i-rich galaxies with masses greater than 1010 M⊙ are found to be antibiased compared to galaxies with ‘normal’ H i content. Interestingly, no such effect is found for lower mass galaxies.