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Astron. Astrophys. 350, 25-30 (1999)

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Spatial and spectral X-ray properties of the powerful radio galaxy Hercules A: environment and jet/ICM interaction

J. Siebert 1,2, N. Kawai 2 and W. Brinkmann 1

1 Max-Planck-Institut für Extraterrestrische Physik, Giessenbachstrasse, D-85740 Garching, Germany
2 Institute of Physical and Chemical Research (RIKEN), 2-1 Hirosawa, Wako, Saitama 351-01, Japan

Received 18 May 1999 / Accepted 21 July 1999


We investigate the X-ray properties of the powerful radio galaxy Hercules A (3C 348) using ROSAT HRI, PSPC and ASCA observations. The ASCA data are well fit by a thermal plasma model with a temperature of about 4.3 keV and abundances 0.4 solar. The HRI observation clearly reveals extended and elongated X-ray emission. For radii greater than 10 arcsec, the surface brightness profile perpendicular to the elongation is well fit by an isothermal [FORMULA]-model with [FORMULA] and a core radius of [FORMULA] kpc. We derive a total mass of the putative cluster of [FORMULA] [FORMULA] and a gas mass fraction of about 18 per cent. The inner part of the surface brightness profile clealry reveals the presence of a point source, which contributes [FORMULA]8 per cent to the total flux. The 0.1-2.4 keV luminosity of the point-like and the extended emission is [FORMULA] and [FORMULA] erg s-1, respectively. After subtracting the cluster X-ray emission from the HRI image, residual structures are visible, which partly coincide with the radio jet and lobes. This indicates an interaction of the radio jet with the intracluster medium.

Key words: galaxies: active – galaxies: individual: Hercules A – X-rays: general – radio continuum: galaxies

Correspondence to: J. Siebert (jos@mpe.mpg.de)

© European Southern Observatory (ESO) 1999

Online publication: September 24, 1999