不再过度质量：小红点宿主黑洞种子质量可与单一超大质量恒星相当
Overmassive No More: The Case for Little Red Dots Hosting Black Hole Seeds as Massive as Single Supermassive Stars
- Institute for Astronomy, University of Hawai‘i（夏威夷大学天文研究所）
- Department of Astrophysical Sciences, Princeton University（普林斯顿大学天体物理科学系）
- Max-Planck-Institut für Astronomie（马克斯·普朗克天文学研究所）
- Institute of Science and Technology Austria (ISTA)（奥地利科学技术研究院）
- Department of Astronomy, The University of Texas at Austin（德克萨斯大学奥斯汀分校天文学系）
- Cosmic Frontier Center, The University of Texas at Austin（德克萨斯大学奥斯汀分校宇宙前沿中心）
- MIT Kavli Institute for Astrophysics and Space Research（麻省理工学院卡弗里天体物理学与空间研究研究所）
- David A. Dunlap Department of Astronomy & Astrophysics, University of Toronto（多伦多大学大卫·A·邓普克天文学与天体物理学系）
- Cosmic Dawn Center (DAWN)（宇宙黎明中心）
- Niels Bohr Institute, University of Copenhagen（哥本哈根大学尼尔斯·玻尔研究所）
- Department of Astronomy, University of Florida（佛罗里达大学天文学系）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
本文通过伪光球模型解释小红点连续谱，拟合117个天体的中心引擎，得到质量约10^4-5太阳质量，与单一超大质量恒星一致，表明LRDs可能直接揭示重黑洞种子的诞生。
AI中文摘要：
小红点（LRDs）展现出不同于任何已知类星体或星系的独特性质，这促使人们为其中心引擎提出新的质量估计方法。受其与恒星现象相似性的启发，本文将LRD连续谱解释为伪光球层产生的辐射。我们为宿主扣除后的LRD中心引擎（“黑洞恒星”，BH*s）拟合定制恒星大气模型，该样本由117个天体堆叠而成。典型的BH*连续谱可由温度范围较窄（$T_{\rm eff}\approx4200-4800$ K）的模型很好地拟合，其热光度约为$10^{43-45}$ erg s$^{-1}$，由此推断伪光球半径约为$700-2000$ au。基于这些参数，我们探索了四种推导BH*质量的方法：1）利用大气模型的表面重力；2）依据其与超爱丁顿现象的相似性；3）近似外流物质的逃逸速度；4）利用缺乏光变来约束动力学时间。对于典型的BH*，所有这些方法均得到高度一致的质量，约为$10^{4-5}\\,M_\odot$，这意味着其光度高度超爱丁顿，$L_{\rm{bol}}/L_{\rm{Edd}}\sim5-50$。这些质量估计将BH*置于黑洞质量与宿主星系恒星质量之间局部标度关系的弥散范围内，为那些高出该关系$2-3$ dex的“过度质量”黑洞提供了一种自洽的替代方案。至关重要的是，我们推导的质量与BH*起源于单一超大质量恒星（SMSs）的图景一致，由于广义相对论不稳定性，SMSs的质量不能超过约$10^{5-6}\\,M_\odot$。此外，对于我们推导的$L_{\rm bol}/L_{\rm Edd}$，LRD光度函数的尖锐截断与SMS的最大理论质量相匹配。因此，通过LRDs，我们可能正在直接观测重黑洞种子的诞生。
英文摘要：
Little Red Dots (LRDs) display singular properties unlike any known class of AGN or galaxies, motivating novel mass estimators for their central engines. Inspired by their similarities to stellar phenomena, here we interpret the LRD continuum as being produced by a pseudo-photosphere. We fit tailored stellar atmosphere models to host-subtracted LRD central engines ("black hole stars," BH*s) represented by stacks of $117$ objects. Typical BH* continuum spectra are well fit by models in a narrow range of temperatures ($T_{\rm eff}\approx4200-4800$ K), with bolometric luminosities $\approx10^{43-45}$ erg s$^{-1}$, implying pseudo-photospheric radii $\approx700-2000$ au. Based on these parameters, we explore four different approaches to deriving BH* masses: 1) using the surface gravity from atmosphere models; 2) appealing to the resemblance to super-Eddington phenomena; 3) approximating the escape velocity from the outflowing material; and 4) exploiting the lack of variability to bound the dynamical time. For the typical BH*, all of these methods yield remarkably consistent masses of $\approx10^{4-5}\,M_\odot$, implying a highly super-Eddington luminosity of $L_{\rm{bol}}/L_{\rm{Edd}}\sim5-50$. These mass estimates place BH*s within the scatter of the local scaling relation between black hole mass and host galaxy stellar mass, providing a self-consistent alternative to "overmassive" black holes that lie $2-3$ dex above it. Crucially, our derived masses are consistent with BH*s arising from single supermassive stars (SMSs), whose masses cannot exceed $\approx10^{5-6}\,M_\odot$ due to general relativistic instabilities. Furthermore, for our derived $L_{\rm bol}/L_{\rm Edd}$, the sharp cutoff of the LRD luminosity function matches the maximum theoretical mass of an SMS. With LRDs, we may therefore be directly observing the birth of heavy black hole seeds.
