Detecting the gravitational wave background from primordial black hole dark matter
Abstract
The black hole merging rates inferred after the gravitational-wave detections by Advanced LIGO/VIRGO and the relatively high mass of the progenitors are consistent with models of dark matter made of massive primordial black holes (PBH). PBH binaries emit gravitational waves in a broad range of frequencies that will be probed by future space interferometers (LISA) and pulsar timing arrays (PTA). The amplitude of the stochastic gravitational-wave background expected for PBH dark matter is calculated taking into account various effects such as initial eccentricity of binaries, PBH velocities, mass distribution and clustering. It allows a detection by the LISA space interferometer, and possibly by the PTA of the SKA radio-telescope. Interestingly, one can distinguish this background from the one of non-primordial massive binaries through a specific frequency dependence, resulting from the maximal impact parameter of binaries formed by PBH capture, depending on the PBH velocity distribution and their clustering properties. Moreover, we find that the gravitational wave spectrum is boosted by the width of PBH mass distribution, compared with that of the monochromatic spectrum. The current PTA constraints already rule out broad-mass PBH models covering more than six decades of masses, but evading the microlensing and CMB constraints because black holes appear spatially distributed in clusters.
- Publication:
-
Physics of the Dark Universe
- Pub Date:
- December 2017
- DOI:
- 10.1016/j.dark.2017.10.001
- arXiv:
- arXiv:1610.08479
- Bibcode:
- 2017PDU....18..105C
- Keywords:
-
- Primordial black hole;
- Dark matter;
- Gravitational wave;
- LISA;
- Pulsar timing arrays;
- Astrophysics - Cosmology and Nongalactic Astrophysics;
- Astrophysics - Astrophysics of Galaxies;
- General Relativity and Quantum Cosmology;
- High Energy Physics - Theory
- E-Print:
- 12 pages, 4 figures