Extreme lensing induces spectro-temporal correlations in black-hole signals

Abstract

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 spectro-temporal correlation function which is relevant for unresolved sources. Finally, some observational aspects are discussed and a preliminary assessment of detectability with current and upcoming missions is provided.

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Cited by in corpus (6)

• Measuring Black Hole Light Echoes with Very Long Baseline Interferometry
• Explanation for the absence of secondary peaks in black hole light curve autocorrelations
• Forward Ray Tracing and Hot Spots in Kerr Spacetime
• Exploring black holes with multiple photon spheres by interferometric signatures
• Auto- and cross-correlations for multiple images of corotating hotspots in accretion disks
• Extreme-Lensing Signatures Revealed by Correlations of Simulated Black-Hole Movies