arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 0904.2335astro-ph.HE
收藏

从TeV可变性约束超大质量黑洞的自旋。II。全广义相对论计算

Constraining spins of supermassive black holes from TeV variability. II. fully general relativistic calculations

Yan-Rong Li, Ye-Fei Yuan, Jian-Min Wang, Jian-Cheng Wang, Shu Zhang

摘要:

观测到了来自M87中心的TeV能量光子的快速变化,为估算超大质量黑洞(SMBH)的自旋提供了新的线索.我们扩展了Wang et al.(2008)的研究,包括所有的广义相对论效应。通过数值求解辐射无效吸积流的相对论流体动力学方程组,得到了黑洞周围的辐射场。在Kerr度规中计算了TeV光子对产生的辐射场的光学深度。我们发现,光学深度强烈依赖于:(1)吸积率为$\tautev\propto \dot{M}^{2.5-5.0}$;(2)黑洞自旋;(3)TeV源的位置。结合光学厚度和RIAF辐射的光谱能量分布,可以大大缓解RIAF模型中自旋与其他自由参数的强烈退化。我们将这个模型应用到M87中,发现黑洞的最小比角动量为$a\sim0.8$。本方法适用于M87类源与未来的TeV的排放量的检测,以限制SMBHs的自旋。

英文摘要:

The fast variability of energetic TeV photons from the center of M87 has been detected, offering a new clue to estimate spins of supermassive black holes (SMBHs). We extend the study of Wang et al. (2008) by including all of general relativistic effects. We numerically solve the full set of relativistic hydrodynamical equations of the radiatively inefficient accretion flows (RIAFs) and then obtain the radiation fields around the black hole. The optical depth of the radiation fields to TeV photons due to pair productions are calculated in the Kerr metric. We find that the optical depth strongly depends on: (1) accretion rates as $\tautev\propto \dot{M}^{2.5-5.0}$; (2) black hole spins; and (3) location of the TeV source. Jointly considering the optical depth and the spectral energy distribution radiated from the RIAFs, the strong degeneration of the spin with the other free parameters in the RIAF model can be largely relaxed. We apply the present model to M87, wherein the RIAFs are expected to be at work, and find that the minimum specific angular momentum of the hole is $a\sim0.8$. The present methodology is applicable to M87-like sources with future detection of TeV emissions to constrain the spins of SMBHs.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑