Stochastic gravitationalwave background as a tool for investigating multichannel astrophysical and primordial blackhole mergers
Abstract
The formation of merging binary black holes can occur through multiple astrophysical channels such as, e.g., isolated binary evolution and dynamical formation or, alternatively, have a primordial origin. Increasingly large gravitationalwave catalogs of binary blackhole mergers have allowed for the first model selection studies between different theoretical predictions to constrain some of their model uncertainties and branching ratios. In this work, we show how one could add an additional and independent constraint to model selection by using the stochastic gravitationalwave background. In contrast to model selection analyses that have discriminating power only up to the gravitationalwave detector horizons (currently at redshifts z ≲ 1 for LIGOVirgo), the stochastic gravitationalwave background accounts for the redshift integration of all gravitationalwave signals in the Universe. As a working example, we consider the branching ratio results from a model selection study that includes potential contribution from astrophysical and primordial channels. We renormalize the relative contribution of each channel to the detected event rate to compute the total stochastic gravitationalwave background energy density. The predicted amplitude lies below the current observational upper limits of GWTC3 by LIGOVirgo, indicating that the results of the model selection analysis are not ruled out by current background limits. Furthermore, given the set of population models and inferred branching ratios, we find that, even though the predicted background will not be detectable by current generation gravitationalwave detectors, it will be accessible by thirdgeneration detectors such as the Einstein Telescope and spacebased detectors such as LISA.
 Publication:

Astronomy and Astrophysics
 Pub Date:
 April 2022
 DOI:
 10.1051/00046361/202142208
 arXiv:
 arXiv:2109.05836
 Bibcode:
 2022A&A...660A..26B
 Keywords:

 gravitational waves;
 stars: black holes;
 black hole physics;
 dark matter;
 Astrophysics  Cosmology and Nongalactic Astrophysics;
 Astrophysics  High Energy Astrophysical Phenomena;
 General Relativity and Quantum Cosmology
 EPrint:
 12 pages, 4 figures, accepted in A&