Discovery of an absorbed cluster of galaxies (XMMU J183225.4-103645) close to the Galactic plane with XMM-Newton
Abstract
During an XMM-Newton observation of the galactic supernova remnant G21.5-09 a bright, previously uncatalogued, source (XMMU J183225.4-103645) was detected 18' from G21.5-09. The European Photon Imaging Camera data inside 1' (180 h50-1 kpc) radius are consistent with a source at a redshift of 0.1242 +/- 0.00030.0022 with an optically thin thermal spectrum of temperature 5.8 +/- 0.6 keV and a metal abundance of 0.60 +/- 0.10 solar. This model gives a 2-10 keV luminosity of 3.5+0.8-0.4 h50-2 x 1044 erg s-1. These characteristics, as well as the source extent of 2 farcm0 (350 h50-1 kpc), and the surface brightness profile are consistent with emission from the central region of a moderately rich cluster containing a cooling flow with mass flow rate of ~ 400-600 Msun yr-1. The absorption is (7.9 +/- 0.5) x 1022 atom cm-2, 5 times that inferred from low-resolution HI data but consistent with higher spatial resolution infrared dust extinction estimates. XMMU J183225.4-103645 is not visible in earlier ROSAT observations due to high amount of absorption. This discovery demonstrates the capability of XMM-Newton to map the cluster distribution close to the Galactic plane, where few such systems are known. The ability of XMM-Newton to determine cluster redshifts to 1% precision at z = 0.1 is especially important in optically crowded and absorbed fields such as close to the Galactic plane, where the optical redshift measurements of galaxies are difficult.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- July 2001
- DOI:
- 10.1051/0004-6361:20010649
- arXiv:
- arXiv:astro-ph/0105131
- Bibcode:
- 2001A&A...374...66N
- Keywords:
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- GALAXIES: CLUSTERS: INDIVIDUAL: XMMU J183225.4-103645;
- GALAXIES: INTERGALACTIC MEDIUM;
- X-RAYS: GALAXIES: CLUSTERS;
- Astrophysics
- E-Print:
- Accepted for publication in Astronomy &