We use Chandra X-ray observations to look for evidence of a recoiling black hole from the brightest cluster galaxy in Abell 2261 (A2261-BCG). A2261-BCG is a strong candidate for a recoiling black hole because of its large, flat stellar core, revealed by Hubble Space Telescope imaging observations. We took 100-ksec observations with Chandra and combined it with 35 ksec of archival observations to look for low-level accretion onto a black hole of expected mass $M\sim10^{10}\ M_{\scriptscriptstyle \odot}$ that could possibly be located in one of four off-center stellar knots near the galaxy's center or else in the optical center of the galaxy or in the location of radio emission. We found no X-ray emission arising from a point source in excess of the cluster gas and can place limits on the accretion of any black hole in the central region to a 2-7 keV flux below $4.3 \times 10^{-16}\ \mathrm{erg\ s^{-1}\ cm^{-2}}$, corresponding to a bolometric Eddington fraction of about $10^{-6}$. Thus there is either no $10^{10}\ M_{\scriptscriptstyle \odot}$ black hole in the core of A2261-BCG, or it is accreting at a low level. We also discuss the morphology of the X-ray emitting gas in the cluster and how its asymmetry is consistent with a large dynamic event.

中文翻译：

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钱德拉对阿贝尔 2261 最亮星团星系的观测，这是一个后坐黑洞的候选宿主

我们使用钱德拉 X 射线观测从 Abell 2261 (A2261-BCG) 中最亮的星团星系中寻找反冲黑洞的证据。哈勃太空望远镜的成像观测显示，A2261-BCG 是反冲黑洞的有力候选者，因为它具有大而平坦的恒星核心。我们使用 Chandra 进行了 100 秒的观测，并将其与 35 秒的档案观测相结合，以寻找预期质量为 $M\sim10^{10}\ M_{\scriptscriptstyle \odot}$ 的黑洞的低级吸积可能位于星系中心附近的四个偏离中心的恒星结之一，或者位于星系的光学中心或无线电发射位置。我们发现没有超过星团气体的点源产生的 X 射线发射，并且可以将中心区域任何黑洞的吸积限制为 2-7 keV 通量低于 $4.3 \times 10^{-16} \ \mathrm{erg\ s^{-1}\ cm^{-2}}$，对应于大约 $10^{-6}$ 的热辐射爱丁顿分数。因此，A2261-BCG 的核心要么没有 $10^{10}\ M_{\scriptscriptstyle \odot}$ 黑洞，要么正在低水平吸积。我们还讨论了星团中发射 X 射线的气体的形态，以及它的不对称性如何与大型动态事件相一致。