VIRGO sensitivity to binary coalescences and the Population III black hole binaries

¹ Nicolaus Copernicus Astronomical Center, Bartycka 18, 00716 Warsaw, Poland e-mail: bulik@camk.edu.pl
² Astronomical Observatory, Warsaw University, Al Ujazdowskie 4, 00478 Poland
³ New Mexico State University, Department of Astronomy, 1320 Frenger Mall, Las Cruces, NM 88003, USA
⁴ Tombaugh Fellow

Received: 24 February 2006
Accepted: 4 August 2006

Abstract

Aims.We analyze the properties of VIRGO detector with the aim of studying its ability to search for coalescing black hole binaries. We focus on the remnants of the Population III stars, which currently should be massive black holes (∼), some of them bound in binary systems. The coalescence of such binaries due to emission of gravitational waves may be currently observable.

Methods.We use a binary population synthesis to model the evolution of Population III binaries.

Results. We calculate the signal to noise ratios of gravitational waves emitted by the system in each of the coalescence phase: inspiral, merger and ringdown, and provide simple formulae for the signal to noise ratio as a function of masses of the binaries. We estimate the detection rates for the VIRGO interferometer and also compare them with the estimates for the current LIGO. We show that these expected rates are similar to, or larger than the expected rates from coalescences of Population I and II compact object binaries.