Images and photon ring signatures of thick disks around black holes
read the original abstract
High-frequency very-long-baseline interferometry (VLBI) observations can now resolve the horizon-scale emission from sources in the immediate vicinity of nearby supermassive black holes. Future space-VLBI observations will access highly lensed features of black hole images -- photon rings -- that will provide particularly sharp probes of strong-field gravity. Focusing on the particular case of the supermassive black hole M87*, our goal is to explore a wide variety of accretion flows onto a Kerr black hole and to understand their corresponding images and visibilities. We are particularly interested in the visibility on baselines to space, which encodes the photon ring shape and whose measurement could provide a stringent test of the Kerr hypothesis. We develop a fully analytical model of stationary, axisymmetric accretion flows with a variable disk thickness and a matter four-velocity that can smoothly interpolate between purely azimuthal rotation and purely radial infall. We then determine the observational appearance of such flows, taking care to include the effects of thermal synchrotron emission and absorption. Our images generically display a "wedding cake" structure composed of discrete, narrow photon rings (n=1,2,...) stacked on top of broader primary emission that surrounds a central brightness depression of model-dependent size. We find that the "black hole shadow" is a model-dependent phenomenon -- even for diffuse, optically thin sources -- and should not be regarded as a generic prediction of general relativity. At 230 GHz, the n=1 ring is always visible, but the n=2 ring is sometimes suppressed due to absorption. At 345 GHz, the medium is optically thinner and the n=2 ring displays clear signatures in both the image and visibility domains, identifying this frequency as more promising for future space-VLBI measurements of the photon ring shape.
This paper has not been read by Pith yet.
Forward citations
Cited by 7 Pith papers
-
Photon spheres in dynamical space-times
A covariant framework is developed for photon surfaces in dynamical spherical spacetimes, recovering static limits and applied to collapse and accretion/evaporation models.
-
Light Propagation Prescriptions for Black Hole Movies
Brisk light bridges fast and slow prescriptions by using dominant temporal intervals per lensing band, with mismatches reaching tens of percent when source variability is shorter than delay spreads.
-
Broadened Lensing Rings of Compact Boson Stars: Enhanced Imprint of Accretion Flow in Images and Visibilities
Compact boson stars exhibit broader gravitational lensing rings than black holes, resulting in images and visibilities that depend more strongly on the structure of the accretion flow.
-
Photon Propagation and Black Hole Imaging in Kruglov Nonlinear Electrodynamics
In Kruglov's Born-Infeld-type nonlinear electrodynamics, the effective photon geometry around a charged black hole produces q-dependent shifts in light deflection, shadow radius, and accretion disk images, including s...
-
Photon Propagation and Black Hole Imaging in Kruglov Nonlinear Electrodynamics
In Kruglov nonlinear electrodynamics, small positive values of the parameter q produce stable photon orbits outside the event horizon and modify black hole shadows and relativistic images even when the spacetime metri...
-
Optical Appearance of the Kerr-Bertotti-Robinson Black Hole with a Magnetically Driven Synchrotron Emissivity Model
Kerr-BR black hole images with magnetically coupled synchrotron emissivity show spin- and B-dependent shifts in the inner disk edge, altered lensing rings, and Doppler asymmetries, with retrograde cases displaying wid...
-
Optical images of Kerr-Sen black hole illuminated by thick accretion disks
Increasing charge Q shrinks photon rings and central shadows in Kerr-Sen black hole images while spin creates brightness asymmetry; polarization patterns follow lensing and frame dragging.
discussion (0)
Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.