Suzaku Observation of HCG 62: Temperature, Abundance, and Extended Hard X-Ray Emission Profiles
Abstract
The compact group of galaxies HCG 62(z = 0.0145) was observed for 120ks with Suzaku XIS and HXD-PIN. The XIS spectra for four annular regions were fitted with a two-temperature vapec model with variable abundance, combined with the foreground Galactic component. The Galactic component was described by a two-temperature apec model, and constrained to have a common surface brightness among the four annuli. We confirmed the multi-temperature nature of the intra-group medium, as reported previously, with a doughnut-like high temperature ring at radii 3.3'--6.5'. Abundances of Mg, Si, S, and Fe were well-constrained. We examined the possible ``high-abundance arc'' at ∼ 2' southwest from the center; however, Suzaku data did not confirm it. We suspect that it is a misidentification of an excess hot component in this region as the Fe line. Neither XIS (5-12keV) nor HXD-PIN (12-40keV) gave positive detection of the extended hard X-rays previously reported with ASCA, although our upper limit did not exclude the ASCA result. The 5--12keV intensity in the r < 3.3' region turned out to be 70±19% higher than the nominal CXB level, and Chandra and Suzaku data suggest a concentration of hard X-ray sources with an average photon index of Γ= 1.38±0.06. The cumulative mass of O, Fe, and Mg in the intra-group medium and the metal mass-to-light ratio were compared with those in other groups. The possible role of AGN or galaxy mergers in this group is also discussed.
- Publication:
-
Publications of the Astronomical Society of Japan
- Pub Date:
- January 2008
- DOI:
- 10.1093/pasj/60.sp1.S317
- arXiv:
- arXiv:0711.1454
- Bibcode:
- 2008PASJ...60S.317T
- Keywords:
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- galaxies: abundances;
- galaxies: clusters: individual (HCG 62);
- galaxies: interactions;
- galaxies: intergalactic medium;
- X-rays: diffuse background;
- X-rays: galaxies: clusters;
- Astrophysics
- E-Print:
- 29 pages with 9 figures, accepted for publication in PASJ Vol 60, second Suzaku special issue