围绕超大质量黑洞Sgr A*运行的非热热点
Nonthermal hotspot orbiting the supermassive black hole Sgr A*
- Instituto de Astronomía, Universidad Nacional Autónoma de México（墨西哥国立自治大学天文研究所）
- Instituto Nacional de Astrofísica, Óptica y Electrónica（墨西哥国家天文学、光学和电子学研究所）
- Tsung-Dao Lee Institute, Shanghai Jiao Tong University（上海交通大学李政道研究所）
- School of Physics and Astronomy, Shanghai Jiao Tong University（上海交通大学物理与天文学院）
机构由 AI 辅助整理，请以论文原文为准。
中文总结 AI 辅助
本研究提出吸积盘中轨道运行的热团块解释Sgr A*的三个热点和低光变，通过系统参数探索，确定优选模型为自旋0.5、磁 arrested 盘、热点大小2M、振幅10、轨道半径6M、倾角20度。
中文摘要 AI 辅助
事件视界望远镜最近在230 GHz频率下的毫米波观测解析了银河系中心Sgr A*的最内部结构，揭示了一个环状结构，这与环绕超大质量黑洞的磁化环状结构的同步辐射一致。这些观测揭示了两个关键特征：光子环附近的三个显著热点，以及低光变曲线变异性，其调制指数为$\bar{\sigma}/\bar{\mu} \lesssim 0.1$。最先进的广义相对论磁流体动力学和辐射传输模拟无法同时再现Sgr A*中观测到的三个热点和低光变曲线变异性。我们提出，在吸积盘中形成的轨道运行的热团块可以解释热点现象。我们系统地探索了其物理性质，包括大小、发射振幅、轨道半径、偏心率、速度和轨道平面方向。应用两个观测约束的结果表明，优选模型对应于无量纲自旋$a_{\star}=0.5$的黑洞，磁场采用磁 arrested 盘构型，并存在一个大小为$\sigma_{\rm hs}=2\\,M$、强度振幅$A=10$的热点，在黑洞赤道面上以开普勒速度在$r_{\rm orb}=6 M$处做圆周运动，倾角视角为$i^\circ=20$。
英文摘要
Recent millimeter wavelength observations at 230 GHz by the Event Horizon Telescope have resolved the innermost structure of the Galactic Center, Sgr A*, revealing a ring-like structure consistent with synchrotron emission from a magnetized torus surrounding a supermassive black hole. These observations reveal two key features: three prominent hotspots near the photon ring and low light-curve variability, with a modulation index of $\barσ/\barμ \lesssim 0.1$. State-of-the-art general relativistic magnetohydrodynamic and radiative transfer simulations cannot simultaneously reproduce the three hotspots and low light-curve variability observed in Sgr A*. We propose that an orbiting hot blob, formed in the accretion disk, could account for hotspots. We systematically explore its physical properties, including size, emission amplitude, orbital radius, eccentricity, velocity, and orbital plane orientation. The results -- applying two observational constraints--show that the preferred model corresponds to a black hole with dimensionless spin $a_{\star}=0.5$, a magnetically arrested disk configuration for the magnetic field, and the presence of a hotspot with size $σ_{\rm hs}=2\,M$ and intensity amplitude $A=10$, orbiting circularly at $r_{\rm orb}=6 M$ with Keplerian velocity in the black holes equatorial plane, and an inclination view angle of $i^\circ=20$.
