Photon rings as tests for alternative spherically symmetric geometries with thin accretion disks

Abstract

The imaging by the Event Horizon Telescope (EHT) of the supermassive central objects at the heart of the M87 and Milky Way (Sgr A${}^{\star }$) galaxies, has marked the first step into peering at the photon rings and central brightness depression that characterize the optical appearance of black holes surrounded by an accretion disk. Recently, Vagnozzi et. al. [S.~Vagnozzi, \textit{et al.} arXiv:2205.07787 [gr-qc]] used the claim by the EHT that the size of the {\it shadow} of Sgr A${}^{\star }$ can be inferred by calibrated measurements of the bright ring enclosing it, to constrain a large number of spherically symmetric space-time geometries. In this work we use this result to study some features of the first and second photon rings of a restricted pool of such geometries in thin accretion disk settings. The emission profile of the latter is described by calling upon three analytic samples belonging to the family introduced by Gralla, Lupsasca and Marrone, in order to characterize such photon rings using the Lyapunov exponent of nearly bound orbits and discuss its correlation with the luminosity extinction rate between the first and second photon rings. We finally elaborate on the chances of using such photon rings as observational discriminators of alternative black hole geometries using very long baseline interferometry.

17 pages, 58 figures/images; v2: many comments and additions, version accepted for publication in Physical Review D

References in corpus (22)

• First M87 Event Horizon Telescope Results. I. The Shadow of the Supermassive Black Hole
• First Sagittarius A* Event Horizon Telescope Results. I. The Shadow of the Supermassive Black Hole in the Center of the Milky Way
• Horizon-scale tests of gravity theories and fundamental physics from the Event Horizon Telescope image of Sagittarius A${}^{\ast }$
• First Sagittarius A* Event Horizon Telescope Results. VI: Testing the Black Hole Metric
• Black Hole Shadows, Photon Rings, and Lensing Rings
• First Sagittarius A* Event Horizon Telescope Results. V. Testing Astrophysical Models of the Galactic Center Black Hole
• Global General Relativistic MHD Simulation of a Tilted Black-Hole Accretion Disk
• Notes on non-singular models of black holes
• Magnetically charged black holes from non-linear electrodynamics and the Event Horizon Telescope
• The Shadow of a Spherically Accreting Black Hole
• Lensing by Kerr Black Holes
• Observing the Inner Shadow of a Black Hole: A Direct View of the Event Horizon
• Field sources for Simpson-Visser space-times
• Key Science Goals for the Next-Generation Event Horizon Telescope
• Images and photon ring signatures of thick disks around black holes
• Photon ring test of the Kerr hypothesis: Variation in the ring shape
• Retrolensing by two photon spheres of a black-bounce spacetime
• Universal signatures of singularity-resolving physics in photon rings of black holes and horizonless objects
• Measuring the shape of a black hole photon ring
• Black Hole Photon Rings Beyond General Relativity
• Prediction for the interferometric shape of the first black hole photon ring
• Observational Appearances of Magnetically Charged Black Holes in Born-Infeld Electrodynamics

Cited by in corpus (24)

• The Role of Topological Photon Spheres in Constraining the Parameters of Black Holes
• Quasinormal modes-shadow correspondence for rotating regular black holes
• Effective Potential and Topological Photon Spheres: A Novel Approach to Black Hole Parameter Classification
• Spherically symmetric vacuum solutions in 1-Parameter New General Relativity and their phenomenology
• Trinity of black hole correspondences: Shadows, quasinormal modes, graybody factors, and cautionary remarks
• Weak Gravity Conjecture Validation with Photon Spheres of Quantum Corrected AdS-Reissner-Nordstrom Black Holes in Kiselev Spacetime
• Constraining spherically symmetric metrics by the gap between photon rings
• Shadows and optical appearance of quantum-corrected black holes illuminated by static thin accretions
• Constraints on the black-hole charges of M87* and Sagittarius A* by changing rates of photon spheres can be relaxed
• Spherically symmetric and static black bounces with multiple horizons, throats, and anti-throats in four dimensions
• Gravity versus astrophysics in black hole images and photon rings: Equatorial emissions and spherically symmetric space-times
• Spacetime Measurements with the Photon Ring
• Accurate analytical modeling of light rays in spherically symmetric spacetimes: Applications in the study of black hole accretion disks and polarimetry
• On the Structure of Black Bounces Sourced by Anisotropic Fluids
• Overlapping of photon rings in black hole imaging
• Aberration effect on lower-order images of thin accretion disk in the astrometric approach
• Spherical accretion of a collisionless kinetic gas into a generic static black hole
• Neutral particle collisions near Gibbons-Maeda-Garfinkle-Horowitz-Strominger black holes after shadow observations
• Horizonless star based on regular black hole with finite radius and its observational signatures
• Echoes and quasinormal modes of asymmetric black bounces
• Constraints on the $\gamma$-parameter for the vacuum solution of Cotton gravity with geodesics and shadows
• Imaging the destruction of a rotating regular black hole
• Shadows cast by a class of rotating black bounces with an anisotropic fluid
• Black hole shadows in nonminimally coupled Weyl connection gravity