期刊
PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN
卷 61, 期 5, 页码 1117-1133出版社
OXFORD UNIV PRESS
DOI: 10.1093/pasj/61.5.1117
关键词
galaxies: clusters: intracluster medium; galaxies: clusters: individual (Abell 1795); galaxies: clusters: X-rays
资金
- NASA [NNG05GM92G, NNGG05GP87G, NNG06GC04G]
- STFC [ST/G002339/1] Funding Source: UKRI
- Science and Technology Facilities Council [ST/G002339/1] Funding Source: researchfish
We report Suzaku observations of the galaxy cluster Abell 1795 that extend to r(200) approximate to 2 Mpc, the radius within which the mean cluster mass density is 200 times the cosmic critical density. These observations are the first to probe the state of the intracluster medium in this object at r > 1.3 Mpc. We sample two disjoint sectors in the cluster outskirts (1.3 Mpc < r < 1.9 Mpc) and detect X-ray emission in only one of them to a limiting (3 sigma) soft X-ray surface brightness of B0.5-2keV = 1.8 x 10(-12) erg s(-1) cm(-2) deg(-2), it level less than 20% of the cosmic X-ray background brightness. We trace the run of temperature with radius at r > 0.4 Mpc and find that it falls relatively rapidly (T-deprojected proportional to r(-0.9)), reaching a value about one third of its peak at the largest radius we can measure it. Assuming the intracluster medium is in hydrostatic equilibrium and is polytropic, we find a polytropic index of Gamma = 1.3(-0.2)(+0.3) and we estimate a mass of (4.1(-0.3)(+0.5)) x 10(14) M-circle dot within 1.3 Mpc, somewhat (2.7 sigma) lower than that reported by previous observers. However, our observations provide evidence for departure from hydrostatic equilibrium at radii as small as r similar to 1.3 Mpc approximate to r(500) in this apparently regular and symmetrical cluster.
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