2021-04-23 11:00  P5A-1

Modified Gravity Corrections in Fundamental Orbital Frequencies in Kerr Spacetime

Avani Patel

In Extreme Mass Ratio Inspirals (EMRIs), the equation of motion is expanded in terms of mass-ratio. At leading order, the motion of a Small Compact Object (SCO) inspiraling into a Super Massive Black Hole (SMBH) can be approximated to the geodesic of the background spacetime. In General Relativity, fundamental orbital frequencies Ωr, Ωθ and Ωφ of the orbits traversed by the SCO can be calculated by solving geodesic equations of the Kerr metric. If we formulate any modified gravity theory as a small correction to General Relativity then the spacetime metric around a rotating black hole in that theory can be considered as the Kerr metric with small deformations. This would allow us to calculate fundamental frequencies of geodetic motion of the orbiting object perturbatively i.e. as Kerr frequencies plus small shifts in Kerr frequencies coming from the modified gravity part. Using Action-angle formalism and canonical perturbation theory one can calculate the frequency shifts with respect to Kerr frequencies of the orbital motion around a rotating black hole for the modified gravity theory. Though this procedure is generic and can be readily applied to any deformed Kerr metric, in this talk, I will discuss the calculation of shifts in orbital frequency for a model of Nonlocal gravity.