Low Angular Momentum in Clumpy, Turbulent Disk Galaxies
Abstract
We measure the stellar specific angular momentum jstar=Jstar/Mstar in four nearby (z~0.1) disk galaxies that have stellar masses Mstar near the break M* of the galaxy mass function, but look like typical star-forming disks at z~2 in terms of their low stability (Q~1), clumpiness, high ionized gas dispersion (40-50 km/s), high molecular gas fraction (20-30%) and rapid star formation (~20 Msun/yr). Combining high-resolution (Keck-OSIRIS) and large-radius (Gemini-GMOS) spectroscopic maps, only available at low z, we discover that these targets have about three times less stellar angular momentum than typical local spiral galaxies of equal stellar mass and bulge fraction. Theoretical considerations show that this deficiency in angular momentum is the main cause of their low stability, while the high gas fraction plays a complementary role. Interestingly, the low jstar values of our targets are similar to those expected in the M*-population at higher z from the approximate theoretical scaling jstar~(1+z)^(-1/2) at fixed Mstar. This suggests that a change in angular momentum, driven by cosmic expansion, is the main cause for the remarkable difference between clumpy M*-disks at high z (which likely evolve into early-type galaxies) and mass-matched local spirals.
Cite
@article{arxiv.1508.04768,
title = {Low Angular Momentum in Clumpy, Turbulent Disk Galaxies},
author = {Danail Obreschkow and Karl Glazebrook and Robert Bassett and David B. Fisher and Roberto G. Abraham and Emily Wisnioski and Andrew W. Green and Peter J. McGregor and Ivana Damjanov and Attila Popping and Inger Jorgensen},
journal= {arXiv preprint arXiv:1508.04768},
year = {2015}
}
Comments
4 Figures (including one interactive 3D figure), 1 Table