Angular Momentum-Mass Law for Discs in the Nearby Universe

The relation between galaxy mass and specific angular momentum is a fundamental scaling law of galaxy structure, however accurate observational determinations are made difficult by the fact that most of the specific angular momentum of a typical galaxy resides in its outer regions. I measure the stellar specific angular momenta for 154 disc galaxies at $z=0$ (with $7\lesssim \log\Mstar/\Msun \lesssim 11.5$) using \hi~rotation curves to trace stellar rotation typically beyond $5$ disc scale-lengths. An accurate measurement of $\jstar$ can be derived for $\sim 60\%$ of the sample, while only lower limits can be inferred for the remaining $\sim 40\%$. I derive fits to the specific stellar angular momentum-stellar mass scaling law ($\jstar-\Mstar$) both considering only 92 accurate measurements and taking into account also for 62 lower limits: I find no significant differences in these two cases. I also show how the intrinsic scatter of the $\jstar-\Mstar$ relation varies as a function of the mass-to-light ratio adopted to determine the stellar masses.