Inference on Gravitational Waves from Coalescences of Stellar-Mass Compact Objects and Intermediate-Mass Black Holes

Abstract

Gravitational waves from coalescences of neutron stars or stellar-mass black holes into intermediate-mass black holes (IMBHs) of 100 solar masses represent one of the exciting possible sources for advanced gravitational-wave detectors. These sources can provide definitive evidence for the existence of IMBHs, probe globular-cluster dynamics, and potentially serve as tests of general relativity. We analyse the accuracy with which we can measure the masses and spins of the IMBH and its companion in intermediate-mass ratio coalescences. We find that we can identify an IMBH with a mass above 100 M with 95% confidence provided the massive body exceeds 130 M . For source masses above ∼ 200 M , the best measured parameter is the frequency of the quasi-normal ringdown. Consequently, the total mass is measured better than the chirp mass for massive binaries, but the total mass is still partly degenerate with spin, which cannot be accurately measured. Low-frequency detector sensitivity is particularly important for massive sources, since sensitivity to the inspiral phase is critical for measuring the mass of the stellar-mass companion. We show that we can accurately infer source parameters for cosmologically redshifted signals by applying appropriate corrections. We investigate the impact of uncertainty in the model gravitational waveforms and conclude that our main results are likely robust to systematics.

The missing link in gravitational-wave astronomy

“…IMBHs could be formed via repeated mergers of stars and compact stellar remnants in dense star clusters [ 77 – 80 ]. Using GWs, IMBHs could be observed in a binary with a compact stellar remnant as an intermediate mass-ratio inspiral (IMRI) [ 81 – 84 ], or in a coalescing binary with another IMBH. A DO would enhance the prospects of IMRI detection to tens of events per year, with observations extending out to high redshift.…”

Globular Cluster Binaries and Gravitational Wave Parameter Estimation

“…Chapter 2 was based on work done in collaboration with Fabio Antonini, Ilya Mandel and Vicky Kalogera [1], and benefited from discussions with Sourav Chatterjee, Jonathan Gair, James Guillochon, Fred Rasio and Alberto Sesana. Chapter 3 was based on work done in collaboration with Zhilu Wang, Christopher Berry, Simon Stevenson, John Veitch and Ilya Mandel [3] and benefited from discussions with Michael Pürrer, Tom Callister and Tom Dent. Chapter 4 was based on work done in collaboration with Ilya Mandel and Will M. Farr [2], and benefited from discussions with Christopher Berry, Walter Del Pozzo, Alberto Vecchio, John Veitch, Richard O'Shaughnessy and Chris Pankow.…”