The Effects of Tilt on the Images of Black Hole Accretion Flows

Abstract

We analyze two 3D general-relativistic magnetohydrodynamic accretion simulations in the context of how they would manifest in Event Horizon Telescope (EHT) observations of supermassive black holes. The two simulations differ only in whether the initial angular momentum of the plasma is aligned with the rapid (a = 0.9) spin of the black hole. Both have low net magnetic flux. Ray tracing is employed to generate resolved images of the synchrotron emission. When using parameters appropriate for Sgr A* and assuming a viewing angle aligned with the black hole spin, we find the most prominent difference is that the central shadow in the image is noticeably eccentric in tilted models, with the ring of emission relatively unchanged. Applying this procedure to M87 with a viewing angle based on the large-scale jet, we find that adding tilt increases the angular size of the ring for fixed black hole mass and distance, while at the same time increasing the number of bright spots in the image. Our findings illustrate observable features that can distinguish tilted from aligned flows. They also show that tilted models can be viable for M87, and that not accounting for tilt can bias inferences of physical parameters. Future modeling of horizon-scale observations should account for potential angular momentum misalignment, which is likely generic at the low accretion rates appropriate for EHT targets.

15 pages, 15 figures, 1 table; accepted by ApJ

References in corpus (12)

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• Monitoring the Morphology of M87* in 2009-2017 with the Event Horizon Telescope
• General relativistic MHD simulations of non-thermal flaring in Sagittarius A*
• Magnetically Modified Spherical Accretion in GRMHD: Reconnection-Driven Convection and Jet Propagation
• Photon rings as tests for alternative spherically symmetric geometries with thin accretion disks
• Black Hole Images as Tests of General Relativity: Effects of Plasma Physics
• Spectral and Imaging properties of Sgr A* from High-Resolution 3D GRMHD Simulations with Radiative Cooling
• Silhouettes of invisible black holes
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• Rotation in Event Horizon Telescope Movies
• 3D orbital architecture of a dwarf binary system and its planetary companion
• Blacklight: A General-Relativistic Ray-Tracing and Analysis Tool
• Misaligned magnetized accretion flows onto spinning black holes: Magneto-spin alignment, outflow power, and intermittent jets
• Observational Signatures of Black Hole Accretion: Rotating vs. Spherical Flows with Tilted Magnetic Fields
• The Effects of Tilt on the Time Variability of Millimeter and Infrared Emission from Sagittarius A*
• Electron Heating in the Trans-Relativistic Perpendicular Shocks of Tilted Accretion Flows
• Shock-induced partial alignment in geometrically-thick tilted accretion disks around black holes
• Extreme scale height variations and nozzle shocks in warped disks
• Visible shapes of black holes M87* and SgrA*
• Remarkable correspondence of Sagittarius A* submillimeter variability with a stellar-wind-fed accretion flow model