Cosmological inference using gravitational wave observations alone

Del Pozzo, W., Li, T.G.F. and Messenger, C. (2015) Cosmological inference using gravitational wave observations alone. arXiv, (Unpublished)

Abstract

Gravitational waves emitted during the coalescence of binary neutron star systems are self-calibrating signals. As such they can provide a direct measurement of the luminosity distance to a source without the need for a cosmic distance scale ladder. In general, however, the corresponding redshift measurement needs to be obtained electromagnetically since it is totally degenerate with the total mass of the system. Nevertheless, recent Fisher matrix studies has shown that if information about the equation of state of the neutron stars is available, it is indeed possible to extract redshift information from the gravitational wave signal alone. Therefore, measuring the cosmological parameters in pure gravitational wave fashion is possible. Furthermore, the huge number of sources potentially observable by the Einstein Telescope has led to speculations that the gravitational wave measurement is potentially competitive with traditional methods. The Einstein telescope is a conceptual study for a third generation gravitational wave detector which is designed to yield detections of 103−107 binary neutron star systems per year. This study presents the first Bayesian investigation of the accuracy with which the cosmological parameters can be measured using observations of binary neutron star systems by the Einstein Telescope with the one year of observations. We find by direct simulation of 103 detections of binary neutron stars that, within our simplifying assumptions, H0,Ωm,ΩΛ,w0 and w1 can be measured at the 95% level with an accuracy of ∼8%,65%,39%,80% and 90%, respectively. We also find, by extrapolation, that a measurement accuracy comparable with current measurements by Planck is reached for a number of observed events O(106−7).

• Item Type: Articles
• Status: Unpublished
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Messenger, Dr Christopher
• Authors: Del Pozzo, W., Li, T.G.F., and Messenger, C.
• College/School: College of Science and Engineering > School of Physics and Astronomy
• Research Centre: College of Science and Engineering > School of Physics and Astronomy > Institute for Gravitational Research
• Journal Name: arXiv
• Publisher: arXiv

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