Photon ring structure of rotating regular black holes and no-horizon spacetimes

Abstract

The Kerr black holes possess a photon region with prograde and retrograde orbits radii, respectively, $M\le r_p^{-}\le 3M$ and $3M\le r_p^{+}\le 4M$, and thereby always cast a closed photon ring or a shadow silhouette for $a\le M$. For $a>M$, it is a no-horizon spacetime (naked singularity) wherein prograde orbits spiral into the central singularity, and retrograde orbits produce an arc-like shadow with a dark spot at the center. We compare Kerr black holes' photon ring structure with those produced by three rotating regular spacetimes, viz. Bardeen, Hayward, and nonsingular. These are non-Kerr black hole metrics with an additional deviation parameter of $g$ related to the nonlinear electrodynamics charge. It turns out that for a given $a$, there exists a critical value of $g$, $g_E$ such that $\Delta =0$ has no zeros for $g>g_E$, one double zero at $r=r_E$ for $g=g_E$, respectively, corresponding to a no-horizon regular spacetime and extremal black hole with degenerate horizon. We demonstrate that, unlike the Kerr naked singularity, no-horizon regular spacetimes can possess closed photon ring when $g_E<g\le g_c$, e.g., for $a=0.10M$, Bardeen ($g_E=0.763332M<g\le g_c=0.816792M$), Hayward ($g_E=1.05297M<g\le g_c=1.164846M$) and nonsingular ($g_E=1.2020M<g\le g_c=1.222461M$) no-horizon spacetimes have closed photon ring. These results confirm that the mere existence of a closed photon ring does not prove that the compact object is necessarily a black hole. The ring circularity deviation observable $\Delta C$ for the three no-horizon rotating spacetimes satisfy $\Delta C\le 0.10$ as per the M87* black hole shadow observations. We have also appended the case of Kerr-Newman no-horizon spacetimes (naked singularities) with similar features.

arXiv comment20 pages, 18 figures and 6 tables. Title modified, references and discussions added. Matches the published version in CQG

References in corpus (101)

• First M87 Event Horizon Telescope Results. I. The Shadow of the Supermassive Black Hole
• First M87 Event Horizon Telescope Results. VI. The Shadow and Mass of the Central Black Hole
• First M87 Event Horizon Telescope Results. V. Physical Origin of the Asymmetric Ring
• Formation and evaporation of non-singular black holes
• Regular Black Hole in General Relativity Coupled to Nonlinear Electrodynamics
• Viewing the Shadow of the Black Hole at the Galactic Center
• The Bardeen Model as a Nonlinear Magnetic Monopole
• Regular Magnetic Black Holes and Monopoles from Nonlinear Electrodynamics
• Shadows and strong gravitational lensing: a brief review
• Rotating regular black holes
• Testing the rotational nature of the supermassive object M87* from the circularity and size of its first image
• Measurement of the Kerr Spin Parameter by Observation of a Compact Object's Shadow
• Construction of Regular Black Holes in General Relativity
• Regular electrically charged structures in Nonlinear Electrodynamics coupled to General Relativity
• Regular phantom black holes
• Photon Regions and Shadows of Kerr-Newman-NUT Black Holes with a Cosmological Constant
• Testing the No-Hair Theorem with Observations in the Electromagnetic Spectrum: II. Black-Hole Images
• Regular black holes with a nonlinear electrodynamics source
• Shadow of rotating regular black holes
• Generating rotating regular black hole solutions without complexification
• Light ring stability in ultra-compact objects
• Notes on non-singular models of black holes
• Hunting for extra dimensions in the shadow of M87*
• Non-Singular Charged Black Hole Solution for Non-Linear Source
• Shadow of a rotating braneworld black hole
• Magnetically charged black holes from non-linear electrodynamics and the Event Horizon Telescope
• Shapes and Positions of Black Hole Shadows in Accretion Disks and Spin Parameters of Black Holes
• Null geodesics and shadow of a rotating black hole in extended Chern-Simons modified gravity
• The Current Ability to Test Theories of Gravity with Black Hole Shadows
• Shadows of spherically symmetric black holes and naked singularities
• Rotating black holes in $4D$ Einstein-Gauss-Bonnet gravity and its shadow
• A size of ~1 AU for the radio source Sgr A* at the centre of the Milky Way
• Rotating Regular Black Hole Solution
• Stationary black holes and light rings
• Gravitational deflection of light and shadow cast by rotating Kalb-Ramond black holes
• Photon Rings around Kerr and Kerr-like Black Holes
• A coordinate-independent characterization of a black hole shadow
• Shadows of Einstein-dilaton-Gauss-Bonnet black holes
• Lensing by Kerr Black Holes
• The Shadow of a Rotating Traversable Wormhole
• Black Hole Parameter Estimation from Its Shadow
• Black hole shadow in an expanding universe with a cosmological constant
• Constraining the spin and the deformation parameters from the black hole shadow
• Wormhole Shadows
• Asymptotic Reissner-Nordstrom black holes
• Black hole shadow in a general rotating spacetime obtained through Newman-Janis algorithm
• Shadows of rotating wormholes
• Measuring the Kerr spin parameter of regular black holes from their shadow
• Regular black holes in quadratic gravity
• Shadow cast and deflection of light by charged rotating regular black holes
• Constraints on a charge in the Reissner--Nordström metric for the black hole at the Galactic Center
• Imaging a boson star at the Galactic center
• From static to rotating to conformal static solutions: Rotating imperfect fluid wormholes with(out) electric or magnetic field
• Generic rotating regular black holes in general relativity coupled to nonlinear electrodynamics
• Shapes of rotating nonsingular black hole shadows
• Regular black holes with asymptotically Minkowski cores
• Extreme Gravitational Lensing near Rotating Black Holes
• Shadows of Multi-Black Holes: Analytic Exploration
• Black hole mimicker hiding in the shadow: Optical properties of the $\gamma$-metric
• A General Relativistic Null Hypothesis Test with Event Horizon Telescope Observations of the black-hole shadow in Sgr A*
• On a regular charged black hole with a nonlinear electric source
• Gravastar Shadows
• EHT constraint on the ultralight scalar hair of the M87 supermassive black hole
• Circular geodesics of Bardeen and Ayon-Beato-Garcia regular black-hole and no-horizon spacetimes
• Shadows of rotating five-dimensional charged EMCS black holes
• Asymptotic safety casts its shadow
• On The Nature of the Compact Dark Mass at the Galactic Center
• Image of the Janis-Newman-Winicour naked singularity with a thin accretion disk
• Can we distinguish black holes from naked singularities by the images of their accretion disks?
• On the shadow of rotating traversable wormholes
• Lensing and dynamics of ultra-compact bosonic stars
• Understanding photon sphere and black hole shadow in dynamically evolving spacetimes
• Imaging the Supermassive Black Hole Shadow and Jet Base of M87 with the Event Horizon Telescope
• Does the black hole shadow probe the event horizon geometry?
• Testing Rotating Regular Metrics as Candidates for Astrophysical Black Holes
• Electromagnetic perturbations of black holes in general relativity coupled to nonlinear electrodynamics
• Regular black holes in $f(T)$ Gravity through a nonlinear electrodynamics source
• Shadow of a Naked Singularity without Photon Sphere
• Comment on "Construction of regular black holes in general relativity"
• Analytical approach to strong gravitational lensing from ultracompact objects
• Shadow images of Kerr-like wormholes
• Regular Sources of the Kerr-Schild class for Rotating and Nonrotating Black Hole Solutions
• Shadows of Kerr-like black holes in a modified gravity theory
• On the Observable Shape of Black Hole Photon Rings
• Comment on "Construction of regular black holes in general relativity"
• Shadow and deflection angle of rotating black hole in asymptotically safe gravity
• Black Hole Shadow as a Test of General Relativity: Quadratic Gravity
• Black Hole Shadow Image and Visibility Analysis of Sagittarius A*
• Destroying the event horizon of regular black holes
• Born--Infeld-type electrodynamics and magnetic black holes
• Imaging a non-singular rotating black hole at the center of the Galaxy
• Shadows of CPR black holes and tests of the Kerr metric
• Constraining the tidal charge of brane black holes using their shadows
• Shadow of a rotating squashed Kaluza-Klein black hole
• Shadow of a naked singularity
• Stable Schwarzschild stars as black-hole mimickers
• Extended source effect on microlensing light curves by an Ellis wormhole
• Shadow of charged wormholes in Einstein-Maxwell-dilaton theory
• Spherical photon orbits in the field of Kerr naked singularities
• Profiled spectral lines generated by Keplerian discs orbiting in the Bardeen and Ayon-Beato-Garcia spacetimes
• Coulomb force mediated heat transfer in the near field - geometric effect

Cited by in corpus (40)

• Horizon-scale tests of gravity theories and fundamental physics from the Event Horizon Telescope image of Sagittarius A${}^{\ast }$
• A novel family of rotating black hole mimickers
• Superradiance evolution of black hole shadows revisited
• Tests of Loop Quantum Gravity from the Event Horizon Telescope Results of Sgr A${}^{\ast }$
• Testing Horndeski Gravity from EHT Observational Results for Rotating Black Holes
• Testing Rotating Regular Metrics with EHT Results of Sgr A*
• Strong gravitational lensing by rotating Simpson--Visser black holes
• Superradiant evolution of the shadow and photon ring of Sgr A${}^{\star }$
• An Upper Limit on the Charge of the Black Hole Sgr A* from EHT Observations
• Strong field gravitational lensing by hairy Kerr black holes
• Testing strong gravitational lensing effects by supermassive compact objects with regular spacetimes
• Rotating Black Holes in Horndeski Gravity: Thermodynamic and Gravitational Lensing
• Bardeen Black Holes in the Regularized $4D$ Einstein--Gauss--Bonnet Gravity
• Rotating black holes in general relativity coupled to nonlinear electrodynamics
• Testing black hole mimickers with the Event Horizon Telescope image of Sagittarius A${}^{\ast }$
• Photon rings as tests for alternative spherically symmetric geometries with thin accretion disks
• Observational predictions of LQG motivated polymerized black holes and constraints from Sgr A* and M87*
• Primordial regular black holes as all the dark matter. I. Time-radial-symmetric metrics
• Estimating the cosmological constant from shadows of Kerr--de Sitter black holes
• Parameterizations of black-hole spacetimes beyond circularity
• Testing EGB gravity coupled to bumblebee field and black hole parameter estimation with EHT observations
• Testing black holes in non-linear electrodynamics from the observed quasi-periodic oscillations
• EHT observables as a tool to estimate parameters of supermassive black holes
• Five dimensional rotating regular black holes and shadow
• Signatures of regular black holes from the shadow of Sgr A* and M87*
• Exploring Nonlinear Electrodynamics Theories: Shadows of Regular Black Holes and Horizonless Ultra-Compact Objects
• How different are shadows of compact objects with and without horizons?
• Energy extraction from rotating regular black hole via Comisso-Asenjo mechanism
• Particle motion and tidal force in a non-vacuum-charged naked singularity
• Particle motions around regular black holes
• Parameter estimation of Kerr-Bertotti-Robinson black holes using their shadows
• Viable wormhole solution in Bopp-Podolsky electrodynamics
• Shadows and parameter estimation of rotating quantum corrected black holes and constraints from EHT observation of M87* and Sgr A*
• Instability of a Kerr-type naked singularity due to light and matter accretion and its shadow
• Image of Quantum Improved Regular Kerr Black Hole and Parameter Constraints from EHT Observations
• Signatures of regular black holes from the quasar continuum spectrum
• Observational and theoretical aspects of Superspinars
• Imaging the destruction of a rotating regular black hole
• Optical appearance of regularized compact objects without an exterior photon sphere
• The eye of the storm: A regular Kerr black hole