Determining gravitational wave radiation from close galaxy pairs using a binary population synthesis approach

¹ National Astronomical Observatories/Xinjiang Observatory, Chinese Academy of Sciences, 150 Science 1-Street Urumqi, 830011 Xinjiang, PR China
e-mail: liujinzh@xao.ac.cn
² National Astronomical Observatories/Yunnan Observatory, Chinese Academy of Sciences, 650011 Kunming, PR China
³ Graduate University of the Chinese Academy of Sciences, 100049 Beijing, PR China

Received: 17 June 2011
Accepted: 17 February 2012

Abstract

Context. The early phase of the coalescence of supermassive black hole (SMBH) binaries from their host galaxies provides a guaranteed source of low-frequency (nHz − μHz) gravitational wave (GW) radiation by pulsar timing observations. These types of GW sources would survive the coalescing and be potentially identifiable.

Aims. We aim to provide an outline of a new method for detecting GW radiation from individual SMBH systems based on the Sloan Digital Sky Survey (SDSS) observational results, which can be verified by future observations.

Methods. Combining the sensitivity of the international Pulsar Timing Array (PTA) and the Square Kilometer Array (SKA) detectors, we used a binary population synthesis (BPS) approach to determine GW radiation from close galaxy pairs under the assumption that SMBHs formed at the core of merged galaxies. We also performed second post-Newtonian approximation methods to estimate the variation of the strain amplitude with time.

Results. We find that the value of the strain amplitude h varies from about 10^-14 to 10^-17 using the observations of 20 years, and we estimate that about 100 SMBH sources can be detected with the SKA detector.