Query : 2009A&A...495..721S

2009A&A...495..721S - Astronomy and Astrophysics, volume 495, 721-732 (2009/3-1)

The large-scale shock in the cluster of galaxies Hydra A.


Abstract (from CDS):

We analyzed a deep XMM-Newton observation of the cluster of galaxies Hydra A, focusing on the large-scale shock discovered in Chandra images as a discontinuity in the surface brightness. The shock front can be seen both in the pressure map and in temperature profiles in several sectors. We compared the results of a spherically symmetric hydrodynamic model to surface brightness profiles and temperature jumps across the shock to determine the shock properties. The Mach numbers determined from the temperature jumps are in good agreement with the Mach numbers derived from EPIC/pn surface brightness profiles and previously from Chandra data and are consistent with M∼1.3. In this simple model, the estimated shock age in the different sectors ranges between 130 and 230Myr and the outburst energy between 1.5 and 3x1061erg. The shape of the shock seen in the pressure map can be approximated with an ellipse centered ∼70kpc towards the NE from the cluster center. This is a good simple approximation to the shock shape seen in the Chandra image, although this shape shows additional small deviations from ellipticity. We aimed to develop a better model that can explain the offset between the shock center and the AGN, as well as give a consistent result on the shock age and energy. To this end, we performed 3D hydrodynamical simulations in which the shock is produced by a symmetrical pair of AGN jets launched in a spherical galaxy cluster. As an explanation of the observed offset between the shock center and the AGN, we consider large-scale bulk flows in the intracluster medium, which were included in the simulation. The simulation successfully reproduces the size, ellipticity, and average Mach number of the observed shock front. The predicted age of the shock is 160Myr and the total input energy 3x1061erg. Both values are within the range determined by the spherically symmetric model. To match the observed 70kpc offset of the shock ellipse from the cluster center by large-scale coherent motions, these would need to have a high velocity of 670km/s. We discuss the feasibility of this scenario and offer alternative ways to produce the observed offset and to further improve the simulation.

Abstract Copyright:

Journal keyword(s): X-rays: galaxies: clusters - galaxies: clusters: individual: Hydra A - galaxies: cooling flows - shock waves

Simbad objects: 8

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Number of rows : 8
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
1 ACO 426 ClG 03 19 47.2 +41 30 47           ~ 2203 1
2 ZwCl 0335+0956 ClG 03 38 35.3 +09 57 54           ~ 375 1
3 NAME Hya A LIN 09 18 05.66848602 -12 05 43.8060823   14.38 14.8     ~ 997 1
4 ACO 780 ClG 09 18 30 -12 15.7           ~ 452 0
5 NAME Virgo Cluster ClG 12 26 32.1 +12 43 24           ~ 6508 0
6 M 87 AGN 12 30 49.42338414 +12 23 28.0436859 10.16 9.59 8.63   7.49 ~ 7020 3
7 ACO 3526 ClG 12 48 51.8 -41 18 21           ~ 1045 2
8 ACO 2255 ClG 17 12 50.04 +64 03 10.6           ~ 557 0

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