A High-Abundance Arc in the Compact Group of Galaxies HCG 62: An AGN- or Merger-Induced Metal Outflow?
A High-Abundance Arc in the Compact Group of Galaxies HCG 62: An AGN- or Merger-Induced Metal Outflow?
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DOI：
10.1086/512180
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发表时间：
2007-01
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通讯作者：
Junhua Gu;Haiguang Xu;L. Gu;T. An;Yu Wang;Zhongli Zhang;Xiang-Ping Wu
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作者：
Junhua Gu;Haiguang Xu;L. Gu;T. An;Yu Wang;Zhongli Zhang;Xiang-Ping Wu
我们提出了一个钱德拉研究的金属分布在X射线明亮的致密星系群HCG 62。我们发现扩散X射线辐射在中心星系NGC 4778的核心处达到峰值，并且主要是由热气体的贡献。漫发射在0.25 '内大致对称，由东北-西南方向排列的双面X射线空腔横跨。通过绘制发射硬度比分布图和进行二维谱分析，我们发现在距X射线峰约2'（33.6hkpc）处有一个显著的高丰度弧区，它横跨从南到西北的广大区域，其中一部分大致与西南X射线空洞的外缘重合。在这个弧中测得的平均丰度比在其邻近地区高约2倍，其中的丰度比是很好的一致性与SNIa产量的优势。我们估计，弧中所含的铁质量>3 × 106 h M，占银河系合成铁的>3%。高丰度弧可能是活动星系核活动的结果。然而，也有可能弧是在最近的合并中形成的，正如Spavone及其同事最近的光学运动学研究所暗示的那样，这表明合并可能与活动星系核活动在早期类型星系及其相关星系团或星系团的金属再分布中一样重要。
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 a two-dimensional spectral analysis, we identify a remarkable high-abundance arc region at about 2' (33.6 h kpc) from the X-ray peak that spans over a vast region from south to northwest, a part of which roughly coincides 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 × 106 h M☉, which accounts for >3% of the iron synthesized in the galaxy. The high-abundance arc could have been formed by AGN activity. However, it is also possible that the arc was formed in a recent merger, as implied by the recent optical kinematic study by Spavone and colleagues, which suggests that mergers may be as important as AGN activity in metal redistributions in early-type galaxies and their associated groups or clusters.