2001MNRAS.327.1334V -
Mon. Not. R. Astron. Soc., 327, 1334-1352 (2001/November-2)
The origin of the density distribution of disc galaxies: a new problem for the standard model of disc formation.
VAN DEN BOSCH F.C.
Abstract (from CDS):
We present new models for the formation of disc galaxies that improve upon previous models by following the detailed accretion and cooling of the baryonic mass, and by using realistic distributions of specific angular momentum. Under the assumption of detailed angular momentum conservation, the discs that form have density distributions that are more centrally concentrated than an exponential. We examine the influence of star formation, bulge formation, and feedback on the outcome of the surface brightness distributions of the stars. Low angular momentum haloes yield disc galaxies with a significant bulge component and with a stellar disc that is close to exponential, in good agreement with observations. High angular momentum haloes, on the other hand, produce stellar discs that are much more concentrated than an exponential, in clear conflict with observations. At large radii, the models reveal distinct truncation radii in both the stars and the cold gas. The stellar truncation radii result from our implementation of star formation threshold densities, and are in excellent agreement with observations. The truncation radii in the density distribution of the cold gas reflect the maximum specific angular momentum of the gas that has cooled. We find that these truncation radii occur at Hi surface densities of roughly 1M☉pc–2, in conflict with observations. We examine various modifications to our models, including feedback, viscosity, and dark matter haloes with constant-density cores, but show that the models consistently fail to produce bulge less discs with exponential surface brightness profiles. This signals a new problem for the standard model of disc formation: if the baryonic component of the protogalaxies out of which disc galaxies form has the same angular momentum distribution as the dark matter, discs are too compact.
Abstract Copyright:
The Royal Astronomical Society
Journal keyword(s):
galaxies: formation - galaxies: fundamental parameters - galaxies: kinematics and dynamics - galaxies: spiral - galaxies: structure - dark matter
Simbad objects:
7
Full paper
View the references in ADS
To bookmark this query, right click on this link: simbad:2001MNRAS.327.1334V and select 'bookmark this link' or equivalent in the popup menu