AI 中文总结
该研究在扩展RAR模型下，用Skylight代码计算MCG-06-30-15星系的铁Kα线轮廓，发现致密费米子暗物质核的线特征可与观测匹配，或可区分黑洞与替代致密解。
AI 中文摘要
荧光铁线及其因相对论效应产生的展宽是研究吸积盘内部区域以及致密天体附近时空几何的极佳探针。我们在扩展RAR模型框架下研究铁Kα线轮廓，该模型描述星系尺度上的费米子暗物质分布。最一般的解具有一个致密且高度简并的核，可模拟中心黑洞，同时过渡为由相同粒子组成的延展暗物质晕。我们的目标是对比该场景下产生的线形态与标准克尔黑洞范式预测的结果，特别关注MCG-06-30-15星系。我们使用数值光线追踪代码Skylight计算线轮廓，考虑冷吸积盘的两种不同发射率构型：基于灯柱冕结构的照射轮廓，以及唯象幂律轮廓。产生的轮廓展现出多样的现象学特征，尤其是最致密的费米子核产生的线展宽可与快速旋转黑洞观测到的展宽相媲美。在小于引力半径的半径处存在发射物质，会产生黑洞场景中完全不存在的独特光谱特征。对于MCG-06-30-15星系，我们发现当费米子核的致密性接近临界值时，其与观测到的铁线轮廓宽特征吻合良好。这些结果强化了对独立黑洞自旋测量的需求，结合此类约束，铁线光谱学可能成为区分黑洞与替代致密解（尤其是致密费米子暗物质核）的强大观测工具。
英文摘要
The fluorescent iron line and its broadening due to relativistic effects are excellent probes to study the inner part of an accretion disk and the space-time geometry near the compact object. We investigate the iron K$α$ line profile within the extended RAR model, which describes a fermionic dark matter distribution on galaxy scales. The most general solutions are characterized by a compact and highly degenerate core able to mimic the central black hole, transitioning into an extended halo composed of the same particles. We aim to contrast the resulting line morphologies in this scenario with those predicted by the standard Kerr black hole paradigm. Special attention will be given to MCG-06-30-15 galaxy. We compute the line profile using the numerical ray-tracing code, Skylight. We consider two distinct configurations for the emissivity of the cold accretion disk: an irradiation profile based on the lamp-post corona prescription, and a phenomenological power-law profile. The resulting profiles exhibit a diverse phenomenology. In particular, the most compact fermion cores produce a line broadening comparable to that observed in rapidly rotating black holes. The presence of emitting matter at radii smaller than a gravitational radius yields distinctive spectral features that are entirely absent in the black hole scenario. For MCG-06-30-15 galaxy, we find a good agreement with the observed broad features of the iron line profile, provided the compactness of the fermion core is close to critical. These results reinforce the need for independent black hole spin measurements. Combined with such constraints, iron-line spectroscopy may provide a powerful observational tool to distinguish black holes from alternative compact solutions, in particular compact fermionic dark-matter cores.
CommentsSubmitted to Astronomy & Astrophysics. Comments are welcome
