On the existence of a tight planar relation between stellar specific angular momentum, mass and effective surface brightness for ALFALFA galaxies

Abstract

Measurements of the dependence of stellar specific angular momentum ($j_{\ast }$) on stellar mass ($M_{\ast }$) are presented for large samples of ALFALFA galaxies spanning the stellar mass range $\sim 10^8$-$10^{11}$ M${}_{\odot }$. Accurate estimates of $j_{\ast }$ are generated using measurements of $I$-band effective radius and velocity width of the HI line profile. While the full sample ($N=3607)$ of galaxies yields a $j_{\ast }$-$M_{\ast }$ relation with power-law index $\alpha =0.404\pm 0.03$, it is shown that various sub-samples have indices that are very similar to the best literature results, yet with comparatively lower intrinsic scatters. A galaxy's mean $I$-band surface brightness within its effective radius ($<{\mu }_{\mathrm{eff}}>$) is shown to significantly correlate with $j_{\ast }$-$M_{\ast }$ scatter. A 3D plane fit to all $N=3607$ galaxies in ${\log }_{10}{j}_{\ast }$-${\log }_{10}{M}_{\ast }$-$<{\mu }_{\mathrm{eff}}>$ space yields $j_{\ast }\propto M_{\ast }^{0.589\pm 0.002}<{\mu }_{\mathrm{eff}}{>}^{0.193\pm 0.002}$ with scatter $\sigma =0.089$ dex. $<{\mu }_{\mathrm{eff}}>$-selected sub-samples of size up to $N=1450$ yield power-law $j_{\ast }$-$M_{\ast }$ relations mostly consistent with $\alpha =0.55\pm 0.02$ from the literature and with intrinsic scatter ranging from 0.083 to 0.129 dex. Thus, this paper presents new, highly accurate measurements of the $j_{\ast }$-$M_{\ast }$ relation that can be used to better understand the important roles played by angular momentum in the formation and evolution of galaxies.

12 pages, 7 figures. Accepted for publication in MNRAS