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

Abstract

ABSTRACT Measurements of the dependence of stellar specific angular momentum (j*) on stellar mass (M*) are presented for large samples of galaxies from the Arecibo Legacy Fast ALFA (ALFALFA) survey, spanning the stellar mass range ∼108–1011 M⊙. Accurate estimates of j* are generated using measurements of I-band effective radius and velocity width of the H i line profile. While the full sample (N = 3607) of galaxies yields a j*–M* relation with power-law index α = 0.404 ± 0.03, it is shown that various subsamples 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 (<μeff>) is shown to significantly correlate with j*–M* scatter. A 3D plane fit to all N = 3607 galaxies in log10j*–log10M*–<μeff> space yields j* ∝ M0.589 ± 0.002 <μeff>0.193 ± 0.002 with scatter σ = 0.089 dex. <μeff>-selected subsamples of size up to N = 1450 yield power-law j*–M* relations mostly consistent with α = 0.55 ± 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*–M* relation that can be used to better understand the important roles played by angular momentum in the formation and evolution of galaxies.