Extreme-mass-ratio bursts from the Galactic Centre

Abstract

An extreme-mass-ratio burst (EMRB) is a gravitational wave signal emitted when a compact object passes through periapsis on a highly eccentric orbit about a much more massive body, in our case a stellar mass object about the 4.31 \times 10^6 M_sol massive black hole (MBH) in the Galactic Centre. We investigate how EMRBs could constrain the parameters of the Galaxy's MBH. EMRBs should be detectable if the periapsis is r_p < 65 r_g for a \mu = 10 M_sol orbiting object, where r_g = GM/c^2 is the gravitational radius. The signal-to-noise ratio \rho scales like log(\rho) = -2.7 log(r_p/r_g) + log(\mu/M_sol) + 4.9. For periapses smaller than ~ 10 r_g, EMRBs can be informative, providing good constraints on both the MBH's mass and spin.