Suman Bhattacharya, Salman Habib, Katrin Heitmann
We study dark matter halo profiles using a suite of numerical simulations. We
carry out (gravity-only) simulations of the current concordance LCDM cosmology,
covering a halo mass range of 2.10^(12) to 2.10^(15) solar masses and a
redshift range of z=0-2, dictated primarily by cluster observation
considerations. We find that the shape of the concentration-mass (c-M) relation
flattens at high redshift and this flattening of the slope is naturally
expressed if c is written as a function of the peak height parameter, \nu.
Although the logarithmic slope of the c-M relation changes with redshift, that
of the (c-\nu) relation is effectively constant over the redshift range z=0-2.
The amplitude of c(\nu) varies by about 30% from z=0-2 over the mass range for
massive clusters. The (c-\nu) relation is, however, not universal. We use a
large suite of simulations covering the currently allowed wCDM parameter space
and show that the (c-\nu) relation varies by about +/- 20 % when cosmological
parameters are varied. We find that the distribution of the concentrations can
be well-fit by a Gaussian with variance, \sigma_c=0.33c, where the ratio of the
variance to the mean, \sigma_c/c, is independent of the radius at which the
concentration is defined, the dynamical state of the halo, and the underlying
cosmology. We compare our simulation predictions with current results obtained
from (primarily low) redshift observations and find good agreement with the
observational data for massive clusters of mass > 4.10^(14) solar masses, but
there are disagreements at lower masses. Because of uncertainty in
observational systematics and modeling of baryonic physics, the significance of
these discrepancies remains to be understood. (Abridged)
View original:
http://arxiv.org/abs/1112.5479
No comments:
Post a Comment