Astronomy and Astrophysics – Astrophysics
Scientific paper
2006-10-05
Astrophys.J.669:158-183,2007
Astronomy and Astrophysics
Astrophysics
Accepted for Publication in ApJ; 30 pages, 9 figures. No changes from previous version
Scientific paper
10.1086/521519
We present radial mass profiles within 0.3 r_vir for 16 relaxed galaxy groups-poor clusters (kT range 1-3 keV) selected for optimal mass constraints from the Chandra and XMM data archives. After accounting for the mass of hot gas, the resulting mass profiles are described well by a two-component model consisting of dark matter (DM), represented by an NFW model, and stars from the central galaxy. The stellar component is required only for 8 systems, for which reasonable stellar mass-to-light ratios (M/L_K) are obtained, assuming a Kroupa IMF. Modifying the NFW dark matter halo by adiabatic contraction does not improve the fit and yields systematically lower M/L_K. In contrast to previous results for massive clusters, we find that the NFW concentration parameter (c_vir) for groups decreases with increasing M_vir and is inconsistent with no variation at the 3 sigma level. The normalization and slope of the c_vir-M_vir relation are consistent with the standard LambdaCDM cosmological model with sigma_8 = 0.9. The small intrinsic scatter measured about the c_vir-M_vir relation implies the groups represent preferentially relaxed, early forming systems. The mean gas fraction (f =0.05 +/- 0.01) of the groups measured within an overdensity Delta=2500 is lower than for hot, massive clusters, but the fractional scatter (sigma_f/f=0.2) for groups is larger, implying a greater impact of feedback processes on groups, as expected.
Brighenti Fabrizio
Bullock James S.
Buote David A.
Gastaldello Fabio
Humphrey Philip J.
No associations
LandOfFree
Probing the Dark Matter and Gas Fraction in Relaxed Galaxy Groups with X-ray observations from Chandra and XMM 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 Probing the Dark Matter and Gas Fraction in Relaxed Galaxy Groups with X-ray observations from Chandra and XMM, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Probing the Dark Matter and Gas Fraction in Relaxed Galaxy Groups with X-ray observations from Chandra and XMM will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-655408