ROSAT
PSPC observations of the outer regions of the Perseus cluster of galaxies |
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| Authors: | S Ettori A C Fabian & D A White |
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| Institution: | Institute of Astronomy, Madingley Road, Cambridge CB3 0HA |
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| Abstract: | We present an analysis of four off-axis ROSAT Position Sensitive Proportional Counter (PSPC) observations of the Perseus cluster of galaxies (Abell 426). We detect the surface brightness profile to a radius of 80 arcmin (～2.4 h?150 Mpc) from the X-ray peak. The profile is measured in various sectors and in three different energy bands. First, a colour analysis highlights a slight variation of N H over the region, and cool components in the core and in the eastern sector. We apply the β-model to the profiles from different sectors and present a solution to the, so-called, β-problem. The residuals from an azimuthally-averaged profile highlight extended emission both in the east and in the west, with estimated luminosities of about 8 and 1 ×1043 erg s?1, respectively. We fit several models to the surface brightness profile, including the one obtained from the Navarro, Frenk &38; White potential. We obtain the best fit with the gas distribution described by a power law in the inner, cooling region and a β-model for the extended emission. Through the best-fitting results and the constraints from the deprojection of the surface brightness profiles, we define the radius where the overdensity inside the cluster is 200 times the critical value, r 200, at 2.7 h?150 Mpc. Within 2.3 h?150 Mpc (0.85 r 200), the total mass in the Perseus cluster is 1.2 × 1015 M⊙ and its gas fraction is about 30 per cent. |
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| Keywords: | galaxies: clusters: individual: A426 cooling flows dark matter X-rays: galaxies |
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