Evidence for the Preferential Disruption of Moderately Massive Stars by Supermassive Black Holes
Evidence for the Preferential Disruption of Moderately Massive Stars by Supermassive Black Holes
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DOI：
10.3847/1538-4357/ac35d5
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发表时间：
2021-10
期刊：
影响因子：
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通讯作者：
B. Mockler;Angela A. Twum;K. Auchettl;S. Dodd;K. D. French;J. Law-Smith;E. Ramirez-Ruiz
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文献类型：
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作者：
B. Mockler;Angela A. Twum;K. Auchettl;S. Dodd;K. D. French;J. Law-Smith;E. Ramirez-Ruiz
潮汐破裂事件（TDEs）为探测超大质量黑洞（SMBH）周围的恒星种群提供了一个独特的机会。通过结合光变曲线建模与光谱线信息和知识的恒星在宿主星系的人口，我们能够约束三个TDE的破坏星星的属性。在我们的样品中的TDE具有UV光谱，并且UV N iii与C iii线比率的测量使得能够估计这些事件的氮碳丰度比。我们表明，测得的氮线宽度是一致的起源于中央SMBH分散的被破坏的恒星物质。我们发现，这些氮碳丰度比需要中等质量的恒星（101 -2 M）的破坏。我们确定，这些中等质量的中断是由一个因素的102倍相比，整体恒星人口的后恒星暴星系主机。这意味着SMBH优先破坏更高质量的恒星，可能是由于正在进行的头重脚轻的星星的形成在核星星集群或动力机制，优先运输更高质量的恒星到它们的潮汐半径。
Tidal disruption events (TDEs) provide a unique opportunity to probe the stellar populations around supermassive black holes (SMBHs). By combining light-curve modeling with spectral line information and knowledge about the stellar populations in the host galaxies, we are able to constrain the properties of the disrupted star for three TDEs. The TDEs in our sample have UV spectra, and measurements of the UV N iii to C iii line ratios enabled estimates of the nitrogen-to-carbon abundance ratios for these events. We show that the measured nitrogen line widths are consistent with originating from the disrupted stellar material dispersed by the central SMBH. We find that these nitrogen-to-carbon abundance ratios necessitate the disruption of moderately massive stars (≳1–2 M ⊙). We determine that these moderately massive disruptions are overrepresented by a factor of ≳102 when compared to the overall stellar population of the post-starburst galaxy hosts. This implies that SMBHs are preferentially disrupting higher mass stars, possibly due to ongoing top-heavy star formation in nuclear star clusters or to dynamical mechanisms that preferentially transport higher mass stars to their tidal radii.