Query : 2005A&A...430..385B

2005A&A...430..385B - Astronomy and Astrophysics, volume 430, 385-397 (2005/2-1)

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


Abstract (from CDS):

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 β-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 ∼0.5Gyr old. The cluster is thus perhaps the best X-ray observed candidate so far of an intermediate mass ratio, moderate impact parameter merger.

Abstract Copyright:

Journal keyword(s): galaxies: clusters: general - galaxies: clusters: individual: Abell 3921 - galaxies: intergalactic medium - X-rays: general - X-rays: galaxies: clusters - cosmology: large-scale structure of Universe

Nomenclature: Fig.1: [BSP2005] BGN (Nos BG1, BG2, BG3).

Simbad objects: 4

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Number of rows : 4
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
1 LEDA 100677 GiC 22 48 48.79 -64 23 12.9     16.22 15.59 14.84 ~ 7 0
2 2MASX J22490470-6420356 GiC 22 49 04.7774602464 -64 20 35.624913468   16.57 15.42 14.64 14.00 ~ 12 0
3 2MASX J22495818-6425468 BiC 22 49 58.2289427424 -64 25 46.990072128   16.05   14.06   ~ 18 0
4 ACO 3921 ClG 22 49 59.0 -64 25 48           ~ 149 1

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