arXivDaily arXiv每日学术速递 周一至周五更新
arXiv周末暂无论文更新,休息一下吧,周末愉快~~
arXiv 2102.08289gr-qc
收藏

多毛Kerr黑洞的强场引力透镜

Strong field gravitational lensing by hairy Kerr black holes

Shafqat Ul Islam, Sushant G. Ghosh

摘要:

近年来,由于事件视界望远镜(EHT)的研究结果,人们对黑洞的强引力透镜产生了浓厚的兴趣。EHT的研究结果表明,广义相对论和修正引力理论中的黑洞透镜效应是一致的。这可能有助于我们评估这些模型之间的现象学差异。克尔黑洞也是一些替代引力理论的解决方案,而最近获得的修正克尔黑洞(多毛克尔黑洞),它避开了无毛定理,是由于来自周围流体的额外来源,如暗物质,具有守恒的能量动量张量(EMT)。这些毛茸茸的克尔黑洞也可能是另一种引力理论的解决方案。本文将前人关于Kerr黑洞在强偏转极限下的引力透镜效应的研究推广到具有偏离参数$α$和主发$\ell_0$的多毛Kerr黑洞.有趣的是,偏转系数$\bar{a}$分别随着$\ell_0$和$α$的增加而增加和减小。$\bar{b}$与$\ell_0$和$α$表现出相反的行为。我们还发现偏转角$α_D$、角位置$θ_{\infty}$和$u_{m}$随着$α$的减小而减小,而角间距$s$随着$α$的增大而增大。我们将我们的结果与Kerr黑洞的结果进行了比较,并应用该方法讨论了超大质量黑洞Sgr A* 和M87* 的天体物理结果.我们观察到,Sgr A* 的角位置与Kerr黑洞角位置的偏差不超过$2.6~μ$,M87* 的角位置与Kerr黑洞角位置的偏差不超过$1.96~μ$,这是目前EHT观测所不能分辨的。

英文摘要:

Recent times witnessed a surge of interest in strong gravitational lensing by black holes due to the Event Horizon Telescope (EHT) results, which suggest comparing the black hole lensing in general relativity and modified gravity theories. This may help us to assess the phenomenological differences between these models. A Kerr black hole is also a solution to some alternative theories of gravity, while recently obtained modified Kerr black holes (hairy Kerr black holes), which evade the no-hair theorem, are due to additional sources from surrounding fluid, like dark matter, having conserved energy momentum tensor (EMT). These hairy Kerr black holes may also be solutions to an alternative theory of gravity. We generalize previous work on gravitational lensing by a Kerr black hole in the strong deflection limits to the hairy Kerr black holes, with a deviation parameter $α$ and a primary hair $\ell_0$. Interestingly, the deflection coefficient $\bar{a}$ increases and decreases with increasing $\ell_0$ and $α$ respectively. $\bar{b}$ shows opposite behaviour with $\ell_0$ and $α$. We also find that the deflection angle $α_D$, angular position $θ_{\infty}$ and $u_{m}$ decrease, but angular separation $s$ increases with $α$. We compare our results with those for Kerr black holes, and also apply the formalism to discuss the astrophysical consequences in the context of the supermassive black holes Sgr A* and M87*. We observe that the deviations of the angular positions from that of the Kerr black hole are not more than $2.6~μ$as for Sgr A* and $1.96~μ$as for M87*, which are unlikely to be resolved by the current EHT observations.

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。

↑