AI 中文总结
研究利用解析辐射流体动力学外流模型，探讨由黑洞超临界吸积驱动的光学厚外流能否解释小红点（LRDs），发现该模型能较好匹配观测，如光度、温度、发射线FWHM及巴尔末线系间断等，为LRDs物理起源研究提供新视角。
AI 中文摘要
近期詹姆斯·韦布空间望远镜（JWST）的观测揭示了一类被称为小红点（LRDs）的致密光学红色源。一种流行的解释是LRDs包含嵌入致密气态包层中的大质量黑洞，但其包层的物理起源仍不清楚。我们提出由黑洞超临界吸积驱动的光学厚外流可以解释该包层。基于一个解析辐射流体动力学外流模型，我们将外流性质与黑洞质量\(M\)和无量纲吸积率\(\dot{m}\)联系起来。当\(M\sim10^5 - 10^7\,M_\odot\)且\(\dot{m}\sim1500 - 5000\)时，外流光球层达到\(10^{43}-10^{45}\,\rm erg\,s^{-1}\)的光度和约\(3000 - 6000\)K的温度，与LRDs中观测到的红色光学连续谱有效匹配。光球层之外厚散射区域的存在对于解读LRDs的独特性质至关重要。对于每个天体，如果从观测到的光度和温度推导\(M\)和\(\dot{m}\)，同时考虑运动学展宽和散射效应，该模型预测发射线半高宽（FWHM）与超过80%的天体观测结果在1.5倍因子内一致。此外，通过Cloudy模拟，我们发现光球层之外的部分电离气体产生的巴尔末线系间断与测量结果大致相符。
英文摘要
Recent JWST observations have revealed a population of compact, optically red sources known as Little Red Dots (LRDs). A popular interpretation is that LRDs host massive black holes embedded in dense gaseous envelopes, yet the physical origin of such envelopes remains unclear. We propose that the optically thick outflow driven by supercritical accretion onto black holes may explain the envelope. Based on an analytic radiative hydrodynamic outflow model, we relate the outflow properties to the black hole mass $M$ and dimensionless accretion rate $\dot{m}$. With $M\sim10^5-10^7\,M_\odot$ and $\dot m \sim 1500-5000$, the outflow photosphere reaches luminosities of $10^{43}-10^{45}\,\rm erg\,s^{-1}$ and temperatures of $\sim 3000-6000$ K, effectively matching the red optical continua observed in LRDs. The presence of a thick scattering region beyond the photosphere is central to deciphering the distinctive properties of LRDs. For each object, if one derives $M$ and $\dot{m}$ from the observed luminosity and temperature, while accounting for both kinematic broadening and scattering effects, the model predicts an emission line FWHM consistent with observations within a factor of 1.5 for more than 80\% objects. Furthermore, with Cloudy simulations, we find that the partially ionized gas beyond the photosphere produces Balmer breaks broadly consistent with measurements.
CommentsAccepted for publication in ApJL
