MG12 - Talk detail
 

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Abstract

Unravelling Binary Evolution from Gravitational-Wave Signals and Source Statistics

The next generation of ground-based gravitational-wave detectors are likely to detect gravitational waves from the coalescences of compact objects: neutron stars and stellar-mass black holes. The best estimates for detection rates for systems involving black holes come from population-synthesis models constrained by electromagnetic observations. However, these estimates are affected by a number of astrophysical uncertainties, ranging from natal kick velocities to common-envelope efficiency. We describe the state of the art for predictions of rates of compact binary coalescences and report on initial efforts to develop a framework for converting gravitational-wave observations into improved constraints on astrophysical parameters.

Probing light seeds of massive black holes with gravitational waves

Identifying the properties of the first generation of seeds of massive black holes is key to understanding the merger history and growth of galaxies. Mergers between ~100 solar-mass seed black holes generate gravitational waves in the 0.1--10 Hz band that lies between existing ground-based detectors (e.g., LIGO, Virgo, and GEO 600) and the planned space-based gravitational wave detector LISA. As such, these sources are targets for proposed third-generation ground-based instruments, such as the Einstein Telescope which is currently in design study. Using galaxy merger trees and four different models of black hole accretion --- which are meant to illustrate the potential of this new type of source rather than to yield precise event-rate predictions --- we find that such detectors could observe a few to a few tens of seed black-hole merger events in three years and provide, possibly unique, information on the evolution of structure in the corresponding era. We show further that a network of detectors may be able to measure the luminosity distance to sources to a precision of ~ 40%, allowing us to be confident of the high-redshift nature of the sources.

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