An XMM-Newton observation of A3921:: An off-axis merger

被引:26
作者
Belsole, E
Sauvageot, JL
Pratt, GW
Bourdin, H
机构
[1] CEA Saclay, Serv Astrophys, F-91191 Gif Sur Yvette, France
[2] Univ Bristol, HH Wills Phys Lab, Bristol BS8 1TL, Avon, England
[3] Max Planck Inst Extraterr Phys, D-85741 Garching, Germany
[4] Observ Cote Azur, F-06304 Nice 4, France
[5] Univ Roma Tor Vergata, Dipartimento Fis, I-00133 Rome, Italy
关键词
galaxies : clusters : general; galaxies : clusters : individual : Abell 3921; galaxies : intergalactic medium; X-rays : general; X-rays : galaxies : clusters; cosmology : large-scale structure of Universe;
D O I
10.1051/0004-6361:20041275
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We present the results of a detailed analysis of the XMM-Newton observation of the galaxy cluster Abell 3921. The X-ray morphology of the cluster is elliptical, with the centroid offset from the brightest cluster galaxy by 17", and with a pronounced extension toward the NW. Subtraction of a 2D beta-model fit to the main cluster emission reveals a large scale, irregular residual structure in the direction of the extension, containing both diffuse emission from the intra cluster medium, and extended emission from the second and third-brightest cluster galaxies (BG2 and BG3). The greatest concentration of galaxies in the subcluster lies at the extreme northern edge of the residual. The cluster exhibits a remarkable temperature structure, in particular a bar of significantly hotter gas, oriented SE-NW and stretching from the centre of the cluster towards BG2 and BG3. Our detailed study of the morphological and thermal structure points to an off-axis merger between a main cluster and a less massive galaxy cluster infalling from the SE. From comparison of the temperature map with numerical simulations, and with independent calculations based on simple physical assumptions, we conclude that the merging event is similar to 0.5 Gyr old. The cluster is thus perhaps the best X-ray observed candidate so far of an intermediate mass ratio, moderate impact parameter merger.
引用
收藏
页码:385 / U21
页数:16
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