Photon ring autocorrelations
Photon ring autocorrelations
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DOI：
10.1103/physrevd.103.104038
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发表时间：
2020-10
影响因子：
5
通讯作者：
Shahar Hadar;Michael D. Johnson;A. Lupsasca;G. Wong
中科院分区：
文献类型：
--
作者：
Shahar Hadar;Michael D. Johnson;A. Lupsasca;G. Wong
在黑洞存在的情况下，光源沿着多条路径连接到观测者。因此，观测到的亮度波动必须在黑洞图像的不同时间和位置上相互关联。在黑洞周围执行多次轨道的光子出现在观测者天空中的一条关键曲线附近，从而产生光子环。本文提出了一种新的观测值：光子环上强度波动的两点相关函数。本文对随机赤道辐射包围的克尔黑洞进行了相关函数的解析计算，其源统计是由紊流吸积流模拟引起的。结果表明，该两点函数表现出由形状相同的多个峰组成的普遍自相似结构：虽然每个峰的轮廓编码了源中波动的统计特性，但峰的位置和高度完全由黑洞参数决定。测量这些峰值将证明光子环的存在，而不需要解决它的厚度问题，并将提供黑洞质量和自旋的估计。在足够长的时间尺度上进行定期监测，这种测量可以通过对视界望远镜进行适度改进的干涉成像来实现。
In the presence of a black hole, light sources connect to observers along multiple paths. As a result, observed brightness fluctuations must be correlated across different times and positions in black hole images. Photons that execute multiple orbits around the black hole appear near a critical curve in the observer sky, giving rise to the photon ring. In this paper, a novel observable is proposed: the two-point correlation function of intensity fluctuations on the photon ring. This correlation function is analytically computed for a Kerr black hole surrounded by stochastic equatorial emission, with source statistics motivated by simulations of a turbulent accretion flow. It is shown that this two-point function exhibits a universal, self-similar structure consisting of multiple peaks of identical shape: while the profile of each peak encodes statistical properties of fluctuations in the source, the locations and heights of the peaks are determined purely by the black hole parameters. Measuring these peaks would demonstrate the existence of the photon ring without resolving its thickness, and would provide estimates of black hole mass and spin. With regular monitoring over sufficiently long timescales, this measurement could be possible via interferometric imaging with modest improvements to the Event Horizon Telescope.