Another Approach to Test Gravity around a Black Hole

Abstract

Pulsars orbiting around the black hole at our galactic center provide us a unique testing site for gravity. In this work, we propose an approach to probe the gravity around the black hole introducing two phenomenological parameters which characterize deviation from the vacuum Einstein theory. The two phenomenological parameters are associated with the energy momentum tensor in the framework of the Einstein theory. Therefore, our approach can be regarded as the complement to the parametrized post-Newtonian framework in which phenomenological parameters are introduced for deviation of gravitational theories from general relativity. In our formulation, we take the possibility of existence of a relativistic and exotic matter component into account. Since the pulsars can be regarded as test particles, as the first step, we consider geodesic motion in the system composed of a central black hole and a perfect fluid whose distribution is static and spherically symmetric. It is found that the mass density of the fluid and a parameter of the equation of state can be determined with precision with $0.1\%$ if the density on the pulsar orbit is larger than $10^{-9}g/c{\mathrm{m}}^3$.

14 pages, 1 figure, accepted for publication in CQG

References in corpus (5)

• Observation of Gravitational Waves from a Binary Black Hole Merger
• The Confrontation between General Relativity and Experiment
• Can environmental effects spoil precision gravitational-wave astrophysics?
• A Quantitative Test of the No-Hair Theorem with Sgr A* using stars, pulsars, and the Event Horizon Telescope
• Pulsar-black hole binaries: prospects for new gravity tests with future radio telescopes

Cited by in corpus (5)

• Periapsis shifts in dark matter distribution around a black hole
• Shining Light on Quantum Gravity with Pulsar-Black Hole Binaries
• General formulae for the periapsis shift of a quasi-circular orbit in static spherically symmetric spacetimes and the active gravitational mass density
• Extended mass and spheroidal deformation effects on epicyclic frequencies and periapsis shift in quasi-circular orbits
• Test particle motion around a black hole dressed with a spherically symmetric stationary fluid