Probing the Dark Matter and Gas Fraction in Relaxed Galaxy Groups with X-ray observations from Chandra and XMM

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dc.creatorGastaldello, Fabio
dc.creatorBuote, David A.
dc.creatorHumphrey, Philip J.
dc.creatorZappacosta, Luca
dc.creatorBullock, James S.
dc.creatorBrighenti, Fabrizio
dc.creatorMathews, William G.
dc.date2006-10-05
dc.date2007-07-11
dc.date.accessioned2026-07-07T11:42:37Z
dc.date.available2026-07-07T11:42:37Z
dc.descriptionWe 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.
dc.descriptionAccepted for Publication in ApJ; 30 pages, 9 figures. No changes from previous version
dc.identifierhttps://arxiv.org/abs/astro-ph/0610134
dc.identifierhttp://arxiv.org/abs/astro-ph/0610134
dc.identifierAstrophys.J.669:158-183,2007
dc.identifierdoi:10.1086/521519
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/200947
dc.subjectAstrophysics
dc.titleProbing the Dark Matter and Gas Fraction in Relaxed Galaxy Groups with X-ray observations from Chandra and XMM
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