2013/04/30 by T. F. Lagana, T. F. Laganá, N. Martinet +5
Physics and Astronomy · #Astronomy and Astrophysical Research #Electrical and Electromagnetic Research #Galaxies: Formation, Evolution, Phenomena #astro-ph.CO
paper · pdf · doi:10.1051/0004-6361/201220423
Accepted for publication in A&A; 16 pages, 9 figures, 1 table
openalex publication_date 2013/05/14 · arxiv created 2013/05/27 · arxiv updated 2013/05/28 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/31
<i>Aims. <i/>Based on <i>XMM-Newton<i/>, <i>Chandra<i/>, and SDSS data, we investigate the baryon distribution in groups and clusters and its use as a cosmological constraint. For this, we considered a sample of 123 systems with temperatures <i>k<i/><i>T<i/><sub>500<sub/> = 1.0−9.0 keV, total masses in the mass range M<sub>500<sub/> = (~10<sup>13<sup/>-4 × 10<sup>15<sup/>)<i>h<i/><sub>70<sub/><sup>-1<sup/> <i>M<i/><sub>⊙<sub/>, and redshifts 0.02 < <i>z<i/> < 1.3.<i>Methods. <i/>The gas masses and total masses are derived from X-ray data under the assumption of hydrostatic equilibrium and spherical symmetry. The stellar masses are based on SDSS-DR8 optical photometric data. For the 37 systems out of 123 that had both optical and X-ray data available, we investigated the gas, stellar, and total baryon mass fractions inside <i>r<i/><sub>2500<sub/> and <i>r<i/><sub>500<sub/> and the differential gas mass fraction within the spherical annulus between <i>r<i/><sub>2500<sub/> and <i>r<i/><sub>500<sub/>, as a function of total mass. For the other objects, we investigated the gas mass fraction only.<i>Results. <i/>We find that the gas mass fraction inside <i>r<i/><sub>2500<sub/> and <i>r<i/><sub>500<sub/> depends on the total mass. However, the differential gas mass fraction does not show any dependence on total mass for systems with <i>M<i/><sub>500<sub/> > 10<sup>14<sup/> <i>M<i/><sub>⊙<sub/>. The stellar mass fraction inside <i>r<i/><sub>2500<sub/> and <i>r<i/><sub>500<sub/> increases towards low-mass systems more steeply than the <i>f<i/><sub>gas<sub/> decrease with total mass. Adding the gas and stellar mass fractions to obtain the total baryonic content, we find it to increase with cluster mass, reaching the WMAP-7 value for clusters with <i>M<i/><sub>500<sub/> ~ 10<sup>14<sup/> <i>M<i/><sub>⊙<sub/>. This led us to investigate the contribution of the intracluster light to the total baryon budget for lower mass systems, but we find that it cannot account for the difference observed.<i>Conclusions. <i/>The gas mass fraction dependence on total mass observed for groups and clusters could be due to the difficulty of low-mass systems to retain gas inside the inner region (<i>r<i/> < <i>r<i/><sub>2500<sub/>). Because of their shallower potential well, non-thermal processes are more effective in expelling the gas from their central regions outwards. Since the differential gas mass fraction is nearly constant, it provides better constraints for cosmology. Moreover, we find that the gas mass fraction does not depend on redshift at a 2<i>σ<i/> level. Using our total <i>f<i/><sub>b<sub/> estimates, our results imply Ω<sub>m<sub/> < 0.55, and taking the highest significant estimates for <i>f<i/><sub>b<sub/>, Ω<sub>m<sub/> > 0.22.