Astronomy and Astrophysics – Astrophysics
Scientific paper
2006-10-24
Astrophys.J.655:L21-L24,2007
Astronomy and Astrophysics
Astrophysics
Accepted for publication in ApJL. Current version matches ApJL page requirement
Scientific paper
10.1086/511524
We explore the dependence of the ratio of a galaxy's circular velocity, Vcirc, to its central velocity dispersion, sigma_0, on morphology, or equivalently total light concentration. Such a dependence is expected if light traces the mass. Over the full range of galaxy types, masses and brightnesses, and assuming that the gas velocity traces the circular velocity, we find that galaxies obey the relation log(Vcirc/sigma_0)= 0.63-0.11*C28 where C28=5log(r80/r20) and the radii are measured at 80 percent and 20 percent of the total light. Massive galaxies scatter about the Vcirc = sqrt(2)*sigma_0 line for isothermal stellar systems. Disk galaxies follow the simple relation Vcirc/sigma_0=2(1-B/T), where B/T is the bulge-to-total light ratio. For pure disks, C28~2.8, B/T -> 0, and Vcirc~=2*sigma_0. Self-consistent equilibrium galaxy models from Widrow & Dubinski (2005) constrained to match the size-luminosity and velocity-luminosity relations of disk galaxies fail to match the observed Vcirc/sigma_0 distribution. Furthermore, the matching of dynamical models for Vcirc(r)/sigma(r) with observations of dwarf and elliptical galaxies suffers from limited radial coverage and relatively large error bars; for dwarf systems, however, kinematical measurements at the galaxy center and optical edge suggest Vcirc(Rmax) > 2*sigma_0 (in contrast with past assumptions that Vcirc = sqrt(2)*sigma_0 for dwarfs.) The Vcirc-sigma_0-C28 relation has direct implications for galaxy formation and dynamical models, galaxy scaling relations, the mass function of galaxies, and the links between respective formation and evolution processes for a galaxy's central massive object, bulge, and dark matter halo.
Courteau Stephane
Holtzman Jon
McDonald Michael
Widrow Lawrence M.
No associations
LandOfFree
The Bulge-Halo Connection in Galaxies: A Physical Interpretation of the Vcirc-sigma_0 Relation does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with The Bulge-Halo Connection in Galaxies: A Physical Interpretation of the Vcirc-sigma_0 Relation, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The Bulge-Halo Connection in Galaxies: A Physical Interpretation of the Vcirc-sigma_0 Relation will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-377857