A High-Abundance Arc in the Compact Group of Galaxies HCG 62: An AGN- or Merger-Induced Metal Outflow?

We present a Chandra study of the metal distribution in the X-ray bright compact group of galaxies HCG 62. We find that the diffuse X-ray emission is peaked at the core of the central galaxy NGC 4778, and is dominated by the contribution of the hot gas. The diffuse emission is roughly symmetric within ≃ 0.25, which is straddled by double-sided X-ray cavities aligned in the northeast-southwest direction. By mapping the emission hardness ratio distributions and by performing the 2-dimensional spectral analysis, we identify a remarkable high-abundance arc region at about 2 (33.6h 70 kpc) from the X-ray peak that spans over a vast region from south to northwest, a part of which roughly coinciding with the outer edge of the southwest X-ray cavity. The measured average abundance in this arc is higher than that in its neighboring regions by a factor of about 2, and the abundance ratios therein are nicely consistent with the dominance of the SN Ia yields. We estimate that the mass of iron contained in the arc is > 3× 106h 70 M⊙, which accounts for > 3% of the iron synthesized in the galaxy. The highabundance arc could have been formed by the AGN activities. However, it is also possible that the arc was formed in a recent merger as is implied by the recent optical kinematic study (Spavone et al. 2006), which implies that mergers may be as important as AGN activities in metal redistributions in early-type galaxies and their associated groups or clusters. Subject headings: galaxies: clusters: individual (HCG 62) — ISM: abundance — X-ray: galaxies Department of Physics, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, PRC; e-mail: [email protected], [email protected], alfred [email protected], wenyu [email protected], [email protected] Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030, PRC; e-mail: [email protected] National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Beijing 100012, PRC; e-mail: [email protected]