用瞬态事件称量“小红点”
Weighing Little Red Dots with Transient Events
- California Institute of Technology（加州理工学院）
- Massachusetts Institute of Technology（麻省理工学院）
- Center for Astrophysics, Harvard and Smithsonian（哈佛史密松天体物理中心）
- Max-Planck-Institut für Astronomie（马克斯·普朗克天文研究所）
- Institute for Astronomy, University of Hawaii（夏威夷大学天体物理研究所）
机构由 AI 辅助整理，请以论文原文为准。
中文总结 AI 辅助
本研究针对高红移“小红点”（LRDs）的本质争议，提出通过潮汐瓦解事件（TDEs）、准周期爆发（QPEs）等瞬态事件的发生率称量LRDs黑洞质量的方法，计算了三种场景下的事件率，有望通过未来宽场巡天验证，为大质量黑洞早期形成提供线索。
中文摘要 AI 辅助
近期詹姆斯·韦布空间望远镜（JWST）的观测发现了大量红移z≳4的致密红色天体，被称为“小红点”（Little Red Dots, LRDs），其中许多呈现出大质量黑洞（black hole, BH）吸积的特征。这些天体的物理本质及其与寄主星系的关联仍存在争议。我们提出一条通过瞬态现象（如潮汐瓦解事件（tidal disruption events, TDEs）和准周期爆发（quasi-periodic eruptions, QPEs），源于恒星与黑洞周围气体包层的相互作用）来约束其本质的独立途径。这些事件的发生率对黑洞质量极为敏感，为“称量”LRDs提供了方法。我们在三种不同场景下计算了LRDs中预期的TDE和QPE发生率：（1）LRDs确实是超大质量黑洞；（2）LRDs的黑洞质量遵循经典的本地标度关系（观测报告的黑洞质量被高估）；（3）当前观测到的LRDs仅是更大质量低质量黑洞群体的冰山一角。我们发现，不同场景下预测的TDE和QPE发生率存在显著差异，尤其是在存在陡峭恒星尖峰的情况下。假设嵌入Bahcall-Wolf尖峰的Hernquist恒星分布，三种场景下每平方度的预期TDE发生率分别为2.78×10⁻³、1.96×10⁻³和3.37×10⁻² yr⁻¹ deg⁻²，而QPE发生率分别为1.64×10⁻²、4.72×10⁻²和4.96×10⁻¹ yr⁻¹ deg⁻²。即将开展的Euclid、Roman和LSST等宽场巡天可能有能力探测这些高红移瞬态事件并获取光变曲线，这些光变曲线包含了关于LRDs黑洞质量和气体结构的额外信息。恒星瞬态事件将为大质量黑洞的早期形成提供宝贵见解。
英文摘要
Recent JWST observations have revealed a large population of compact red sources at $z \gtrsim 4$, known as Little Red Dots (LRDs), many of which show signatures of accreting massive black holes (BHs). The physical nature of these sources and their connection to host galaxies are under debate. We propose an independent avenue for constraining their nature through transient phenomena, such as tidal disruption events (TDEs) and quasi-periodic eruptions (QPEs), arising from interactions between a star and the gas envelope surrounding the BH. These event rates depend sensitively on BH mass and provide a way to "weigh" LRDs. We calculate the expected TDE and QPE rates in LRDs under three distinct scenarios: (1) LRDs are truly overmassive BHs, (2) LRDs have BH masses following the classical local scaling relations (and the reported BH masses in observations are overestimated), and (3) the currently observed LRDs are only the tip of the iceberg of a larger population of low-mass BHs. We find that the predicted TDE and QPE rates differ dramatically across scenarios, especially in the presence of steep stellar cusps. The expected TDE rates per degree-square, assuming a Hernquist stellar distribution with a Bahcall-Wolf cusp embedded, are $2.78 \times 10^{-3}$, $1.96 \times 10^{-3}$, and $3.37 \times 10^{-2} \, {\rm yr}^{-1} \, {\rm deg}^{-2}$ for the three scenarios, respectively, while the QPE rates are $1.64 \times 10^{-2}$, $4.72 \times 10^{-2}$, and $4.96 \times 10^{-1} \, {\rm yr}^{-1} \, {\rm deg}^{-2}$. Upcoming wide-field surveys with Euclid, Roman, and LSST may be capable of detecting these high-redshift transient events and obtaining light curves, which encode additional information about the BH mass and the gas structure of LRDs. Stellar transient events will provide valuable insight into the early assembly of massive BHs.
