Rapid progress in electromagnetic black-hole observation presents a theoretical challenge: how can the universal signatures of extreme gravitational lensing be distilled from stochastic astrophysical signals With this motivation, the two-point correlation function of specific intensity fluctuations across image positions, times, and frequencies is here considered. The contribution of strongly deflected light rays, those which make up the photon ring, is analytically computed for a Kerr black hole illuminated by a simple geometric-statistical emission model. We subsequently integrate over the image to yield a spectrotemporal correlation function that is relevant for unresolved sources. Finally, some observational aspects are discussed and a preliminary assessment of detectability with current and upcoming missions is provided.
Bibliographical noteFunding Information:
We thank A. Lupsasca for useful comments. We acknowledge financial support by the Data Science Research Center (DSRC) at the University of Haifa. S. Harikesh is supported by a Bloom postdoctoral fellowship. Research by D. C. is partially supported by grants from the German Science Foundation (DFG HA3555-14/1, CH71-34-3) and the Israeli Science Foundation (ISF 2398/19).
© 2023 American Physical Society.
ASJC Scopus subject areas
- Nuclear and High Energy Physics