The Effect of Metallicity on the Detection Prospects for Gravitational Waves
Abstract
Data from the Sloan Digital Sky Survey (~300,000 galaxies) indicate that recent star formation (within the last 1 billion years) is bimodal: half of the stars form from gas with high amounts of metals (solar metallicity) and the other half form with small contribution of elements heavier than helium (~10%-30% solar). Theoretical studies of mass loss from the brightest stars derive significantly higher stellar-origin black hole (BH) masses (~30-80 M sun) than previously estimated for sub-solar compositions. We combine these findings to estimate the probability of detecting gravitational waves (GWs) arising from the inspiral of double compact objects. Our results show that a low-metallicity environment significantly boosts the formation of double compact object binaries with at least one BH. In particular, we find the GW detection rate is increased by a factor of 20 if the metallicity is decreased from solar (as in all previous estimates) to a 50-50 mixture of solar and 10% solar metallicity. The current sensitivity of the two largest instruments to neutron star-neutron star (NS-NS) binary inspirals (VIRGO: ~9 Mpc; LIGO: ~18) is not high enough to ensure a first detection. However, our results indicate that if a future instrument increased the sensitivity to ~50-100 Mpc, a detection of GWs would be expected within the first year of observation. It was previously thought that NS-NS inspirals were the most likely source for GW detection. Our results indicate that BH-BH binaries are ~25 times more likely sources than NS-NS systems and that we are on the cusp of GW detection.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- June 2010
- DOI:
- 10.1088/2041-8205/715/2/L138
- arXiv:
- arXiv:1004.0386
- Bibcode:
- 2010ApJ...715L.138B
- Keywords:
-
- binaries: close;
- gravitation;
- stars: evolution;
- stars: neutron;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- 4 pages of text, 2 figures, 2 tables (ApJ Letters, accepted)