Probing planetarymass primordial black holes with continuous gravitational waves
Abstract
Gravitational waves can probe the existence of planetarymass primordial black holes. Considering a mass range of $[10^{7}10^{2}]M_\odot$, inspiraling primordial black holes could emit either continuous gravitational waves, quasimonochromatic signals that last for many years, or transient continuous waves, signals whose frequency evolution follows a power law and last for $\mathcal{O}$(hoursmonths). We show that primordial black hole binaries in our galaxy may produce detectable gravitational waves for different mass functions and formation mechanisms. In order to detect these inspirals, we adapt methods originally designed to search for gravitational waves from asymmetrically rotating neutron stars. The first method, the FrequencyHough, exploits the continuous, quasimonochromatic nature of inspiraling black holes that are sufficiently light and far apart such that their orbital frequencies can be approximated as linear with a small spinup. The second method, the Generalized FrequencyHough, drops the assumption of linearity and allows the signal frequency to follow a powerlaw evolution. We explore the parameter space to which each method is sensitive, derive a theoretical sensitivity estimate, determine optimal search parameters and calculate the computational cost of allsky and directed searches. We forecast limits on the abundance of primordial black holes within our galaxy, showing that we can constrain the fraction of dark matter that primordial black holes compose, $f_{\rm PBH}$, to be $f_{\rm PBH}\lesssim 1$ for chirp masses between $[4\times 10^{5}10^{3}]M_\odot$ for current detectors. For the Einstein Telescope, we expect the constraints to improve to $f_{\rm PBH}\lesssim 10^{2}$ for chirp masses between [$10^{4}10^{3}]M_\odot$.
 Publication:

arXiv eprints
 Pub Date:
 December 2020
 arXiv:
 arXiv:2012.12983
 Bibcode:
 2020arXiv201212983M
 Keywords:

 Astrophysics  High Energy Astrophysical Phenomena;
 General Relativity and Quantum Cosmology
 EPrint:
 18 pages, 12 figures