Relativistic Signatures of Flux Eruption Events Near Black Holes

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.

Accepted in Galaxies

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Cited by in corpus (8)

• Key Science Goals for the Next-Generation Event Horizon Telescope
• Broadband Multi-wavelength Properties of M87 during the 2018 EHT Campaign including a Very High Energy Flaring Episode
• Using Machine Learning to Link Black Hole Accretion Flows with Spatially Resolved Polarimetric Observables
• Demonstrating Photon Ring Existence with Single-Baseline Polarimetry
• Accretion Flow Morphology in Numerical Simulations of Black Holes from the ngEHT Model Library: The Impact of Radiation Physics
• On the Universality of Energy Extraction from Black Hole Spacetimes
• Fast Transients from Magnetic Disks Around Non-Spinning Collapsar Black Holes
• Extreme magnetic fields around black holes