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2013ApJ...764L..31K - Astrophys. J., 764, L31 (2013/February-3)

The size-virial radius relation of galaxies.

KRAVTSOV A.V.

Abstract (from CDS):

I use the abundance matching ansatz, which has proven to be successful in reproducing galaxy clustering and other statistics, to derive estimates of the virial radius, R200, for galaxies of different morphological types and a wide range of stellar masses. I show that over eight orders of magnitude in stellar mass galaxies of all morphological types follow an approximately linear relation between half-mass radius of their stellar distribution, r 1/2, and virial radius, r1/2~ 0.015 R200, with scatter of ~0.2 dex. Such scaling is in remarkable agreement with the expectation of models that assume that galaxy sizes are controlled by halo angular momentum, r1/2∝λR200, where λ is the spin of galaxy parent halo. The scatter about the relation is comparable with the scatter expected from the distribution of λ. Moreover, I show that when the stellar and gas surface density profiles of galaxies of different morphological types are rescaled by the radius rn= 0.015 R200, the rescaled profiles follow approximately universal exponential (for late types) and de Vaucouleurs (for early types) form with scatter of only ~30%-50% at R ~ 1-3rn . Remarkably, both late- and early-type galaxies have similar mean stellar surface density profiles at R ≳ 1rn. The main difference between their stellar distributions is thus at R < rn. The results of this study imply that galaxy sizes and radial distribution of baryons are shaped primarily by properties of their parent halos and that the sizes of both late-type disks and early-type spheroids are controlled by halo angular momentum.

Abstract Copyright:

Journal keyword(s): galaxies: formation - galaxies: halos - galaxies: structure

Simbad objects: 4

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