Article

Relativistic Signatures of Flux Eruption Events near Black Holes

Zachary GellesBlack Hole Initiative, Harvard University, 20 Garden Street, Cambridge, MA 02138, USAKoushik ChatterjeeBlack Hole Initiative, Harvard University, 20 Garden Street, Cambridge, MA 02138, USAMichael D. JohnsonBlack Hole Initiative, Harvard University, 20 Garden Street, Cambridge, MA 02138, USABart RipperdaCenter for Computational Astrophysics, Flatiron Institute, 162 Fifth Avenue, New York, NY 10010, USAMatthew LiskaCenter for Astrophysics, Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA

2022en

ABI

Abstract

Images of supermassive black holes produced using very long baseline interferometry provide a pathway to directly observing effects of a highly curved spacetime, such as a bright “photon ring” that arises from strongly lensed emission. In addition, the emission near supermassive black holes is highly variable, with bright high-energy flares regularly observed. We demonstrate that intrinsic variability can introduce prominent associated changes in the relative brightness of the photon ring. We analyze both semianalytic toy models and GRMHD simulations with magnetic flux eruption events, showing that they each exhibit a characteristic “loop” in the space of relative photon ring brightness versus total flux density. For black holes viewed at high inclination, the relative photon ring brightness can change by an order of magnitude, even with variations in total flux density that are comparatively mild. We show that gravitational lensing, Doppler boosting, and magnetic field structure all significantly affect this feature, and we discuss the prospects for observing it in observations of M87∗ and Sgr A∗ with the next-generation Event Horizon Telescope.

Identifiers

DOI: 10.3390/galaxies10060107

Citations and references

Cited by 20 references

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