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Astron. Astrophys. 356, 788-794 (2000)

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1. Introduction

The Perseus cluster of galaxies (Abell 426) is one of the best studied clusters, due to its proximity ([FORMULA], [FORMULA] corresponds to [FORMULA] 30 kpc for [FORMULA]) and brightness. Detailed X-ray images were obtained with the Einstein IPC (Branduardi-Raymont et al. 1981) and HRI (Fabian et al. 1981) and the ROSAT PSPC (Schwarz et al. 1992, Ettori, Fabian, White 1999) and HRI (Böhringer et al. 1993; see also Heinz et al. 1998). The cluster has a prominent X-ray surface brightness peak at its center along with cool gas, which is usually interpreted as due to the pressure induced flow of gas releasing its thermal energy via radiation. The cooling flow is centered on the active galaxy NGC1275, containing a strong core-dominated radio source (Per A, 3C 84) surrounded by a lower surface brightness halo (e.g. Pedlar et al. 1990, Sijbring 1993). Analysis of the ROSAT HRI observations of the central arcminute has shown that the X-ray emitting gas is displaced by the bright radio emitting regions (Böhringer et al. 1993), suggesting that the cosmic ray pressure is at least comparable to that of the hot intracluster gas. Many other studies explored correlations of X-ray, radio, optical, and ultraviolet emission (see e.g. McNamara, O'Connell & Sarazin, 1996 and references therein). In this contribution, we discuss asymmetric structure in the X-ray surface brightness within [FORMULA] 5 arcminutes of NGC 1275 and suggest that buoyant bubbles of relativistic plasma may be important in defining the properties of this structure.

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© European Southern Observatory (ESO) 2000

Online publication: April 17, 2000