Suzaku Observation of HCG 62: Temperature, Abundance, and Extended Hard X-Ray Emission Profiles
Isobe, Naoki; Hoshino, Akio; Sato, Kosuke; Fukazawa, Yasushi; Nakazawa, Kazuhiro; Hughes, John P.; Ohashi, Takaya; Awaki, Hisamitsu; Yamasaki, Noriko Y.; Kawaharada, Madoka; Kawano, Naomi; Ishisaki, Yoshitaka; Matsushita, Kyoko; Ota, Naomi; Tamura, Takayuki; Tokoi, Kazuyo; Egawa, Chihiro
Japan, United States
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.