arXiv subjects

Tomohito Suzuki

Publications and source records attributed to Tomohito Suzuki.

3 recordsLinked to original sources

arXiv2016

Nonradial stability of marginal stable circular orbits in stationary axisymmetric spacetimes

We study linear nonradial perturbations and stability of a marginal stable circular orbit (MSCO) such as the innermost stable circular orbit (ISCO) of a test particle in stationary axisymmetric spacetimes which possess a reflection symmetry with respect to the equatorial plane. The proposed approach is applied to Kerr solution and Majumdar-Papapetrou solution to Einstein equation. Finally, we reexamine MSCOs for a modified metric of a rapidly spinning black hole that has been recently proposed by Johannsen and Psaltis [PRD, 83, 124015 (2011)]. We show that, for the Johannsen and Psaltis's model, circular orbits that are stable against radial perturbations for some parameter region become unstable against vertical perturbations. This suggests that the last circular orbit for this model may be larger than the ISCO.

gr-qc↗

arXiv2015

Marginally stable circular orbit of a test body in spherically symmetric and static spacetimes

We study a marginally stable circular orbit (MSCO) such as the innermost stable circular orbit (ISCO) of a timelike geodesic in any spherically symmetric and static spacetime. It turns out that the metric components are separable from the constants of motion along geodesics. We show also that a metric component $g_{rr}$ with a radial coordinate $r$ does not affect MSCOs. This suggests that, as a test of gravity, any ISCO measurement may be put into the same category as gravitational redshift experiments. MSCOs for exact solutions to the Einstein's equation are also mentioned.

gr-qc↗

arXiv2015

Application of Sturm's theorem to marginal stable circular orbits of a test body in spherically symmetric and static spacetimes

In terms of Sturm's theorem, we reexamine a marginal stable circular orbit (MSCO) such as the innermost stable circular orbit (ISCO) of a timelike geodesic in any spherically symmetric and static spacetime. MSCOs for some of exact solutions to the Einstein's equation are discussed. Strum's theorem is explicitly applied to the Kottler (often called Schwarzschild-de Sitter) spacetime. Moreover, we analyze MSCOs for a spherically symmetric, static and vacuum solution in Weyl conformal gravity.

gr-qc↗