2006ApJ...641..756K -
Astrophys. J., 641, 756-762 (2006/April-3)
A cluster of galaxies hiding behind M31: XMM-Newton observations of RX J0046.4+4204.
KOTOV O., TRUDOLYUBOV S. and VESTRAND W.T.
Abstract (from CDS):
We report on our serendipitous discovery with the XMM-Newton Observatory of a luminous X-ray-emitting cluster of galaxies that is located behind the Andromeda galaxy (M31). X-ray emission from the cluster was detected previously by ROSAT and cataloged as RX J0046.4+4204, but it was not recognized as a galaxy cluster. The much greater sensitivity of our XMM-Newton observations revealed diffuse X-ray emission that extends at least 5' and has a surface brightness profile that is well fit by the α-β model with β=0.70±0.08, a core radius rc=56''±16'', and α=1.54±0.25. A joint global spectral fit of the EPIC MOS1, MOS2, and pn observations with the Mewe-Kaastra-Liedahl plasma emission model gives a cluster temperature of 5.5±0.5 keV. The observed spectra also show high significance iron emission lines that yield a measured cluster redshift of z=0.290 with 2% accuracy. For a cosmological model with H0=71 km/s/Mpc, ΩM=0.3, and ΩΛ=0.7, we derive a bolometric luminosity of LX=(8.4±0.5)x1044 ergs/s. This discovery of a cluster behind M31 demonstrates the utility of X-ray surveys for finding rich clusters of galaxies, even in directions of heavy optical extinction.
Abstract Copyright:
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Journal keyword(s):
galaxies: clusters: individual (RX J0046.4+4204) - Galaxies: Intergalactic Medium - X-Rays: Galaxies: Clusters
Simbad objects:
8
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