Black Hole Shadow as a Test of General Relativity: Quadratic Gravity

Abstract

Observations of the black hole shadow of supermassive black holes, such as Sagittarius A* at the center of our Milky Way galaxy, allow us to study the properties of black holes and the nature of strong-field gravity. According to the Kerr hypothesis, isolated, stationary, and axisymmetric astrophysical black holes are described by the Kerr metric. The Kerr hypothesis holds in General Relativity and in some modified gravity theories, but there are others in which it is violated. In principle, black hole shadow observations can be used to determine if the Kerr metric is the correct description for black holes, and in turn, they could be used to place constraints on modified gravity theories that do not admit the Kerr solution. We here investigate whether black hole shadow observations can constrain deviations from general relativity, focusing on two well-motivated modified quadratic gravity theories: Einstein-dilaton-Gauss-Bonnet gravity and dynamical Chern-Simons gravity. We show that current constraints on Einstein-dilaton-Gauss-Bonnet gravity are stronger than any that could be placed with black hole shadow observations of supermassive black holes. We also show that the same holds for dynamical Chern-Simons gravity through a systematic bias and a likelihood analysis when considering slowly-rotating supermassive black holes. However, observations of more rapidly-rotating black holes, with dimensionless spins $|\vec{J}|/M^2\simeq 0.5$, could be used to better constrain dynamical Chern-Simons gravity.

21 pages, 5 figures. Submitted to CQG

References in corpus (26)

• The Confrontation between General Relativity and Experiment
• Dynamical Chern-Simons Modified Gravity I: Spinning Black Holes in the Slow-Rotation Approximation
• Extreme Gravity Tests with Gravitational Waves from Compact Binary Coalescences: (II) Ringdown
• 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
• Rotating Black Holes in Dilatonic Einstein-Gauss-Bonnet Theory
• Non-Spinning Black Holes in Alternative Theories of Gravity
• Extreme Gravity Tests with Gravitational Waves from Compact Binary Coalescences: (I) Inspiral-Merger
• Interferometric Imaging Directly with Closure Phases and Closure Amplitudes
• Shadows of Einstein-dilaton-Gauss-Bonnet black holes
• Slowly-Rotating Black Holes in Einstein-Dilaton-Gauss-Bonnet Gravity: Quadratic Order in Spin Solutions
• Imaging the Schwarzschild-radius-scale Structure of M87 with the Event Horizon Telescope using Sparse Modeling
• Extreme- and Intermediate-Mass Ratio Inspirals in Dynamical Chern-Simons Modified Gravity
• Kerr Black Holes are Not Unique to General Relativity
• Higher-Derivative Corrected Black Holes: Perturbative Stability and Absorption Cross-Section in Heterotic String Theory
• New Constraint on Scalar Gauss-Bonnet Gravity and a Possible Explanation for the Excess of the Orbital Decay Rate in a Low-Mass X-ray Binary
• Super-resolution Full Polarimetric Imaging for Radio Interferometry with Sparse Modeling
• Testing Chern-Simons Modified Gravity with Gravitational-Wave Detections of Extreme-Mass-Ratio Binaries
• Testing Gravity with Quasi Periodic Oscillations from accreting Black Holes: the Case of Einstein-Dilaton-Gauss-Bonnet Theory
• Kerr black holes with synchronised hair: an analytic model and dynamical formation
• Imaging an Event Horizon: submm-VLBI of a Super Massive Black Hole
• Dynamical Imaging with Interferometry
• Superresolution Interferometric Imaging with Sparse Modeling Using Total Squared Variation --- Application to Imaging the Black Hole Shadow
• The exact dynamical Chern Simons metric for a spinning black hole possesses a fourth constant of motion: A Dynamical-Systems-Based Conjecture
• Principal Component Analysis as a Tool for Characterizing Black Hole Images and Variability
• Time Domain Filtering of Resolved Images of Sgr A*

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• Kerr black holes with synchronised Proca hair: lensing, shadows and EHT constraints
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