The Time Delay Distribution and Formation Metallicity of LIGOVirgos Binary Black Holes
Abstract
We derive the first constraints on the time delay distribution of binary black hole (BBH) mergers using the LIGOVirgo GravitationalWave Transient Catalog. Assuming that the progenitor formation rate follows the star formation rate (SFR), the data favor that 43100 of mergers have delay times <4.5 Gyr (90 credibility). Adopting a model for the metallicity evolution, we derive joint constraints for the metallicitydependence of the BBH formation efficiency and the distribution of time delays between formation and merger. Short time delays are favored regardless of the assumed metallicity dependence, although the preference for short delays weakens as we consider stricter lowmetallicity thresholds for BBH formation. For a p() ^{1} time delay distribution and a progenitor formation rate that follows the SFR without metallicity dependence, we find that _{min} < 2.2 Gyr, whereas considering only the lowmetallicity Z < 0.3 Z SFR, _{min} < 3.0 Gyr (90 credibility). Alternatively, if we assume long time delays, the progenitor formation rate must peak at higher redshifts than the SFR. For example, for a p() ^{1} time delay distribution with _{min} 4 Gyr, the inferred progenitor rate peaks at z > 3.9 (90 credibility). Finally, we explore whether the inferred formation rate and time delay distribution vary with BBH mass.
 Publication:

The Astrophysical Journal
 Pub Date:
 June 2021
 DOI:
 10.3847/20418213/ac05c4
 arXiv:
 arXiv:2105.06491
 Bibcode:
 2021ApJ...914L..30F
 Keywords:

 Gravitational waves;
 Gravitational wave astronomy;
 Astrophysical black holes;
 Stellar mass black holes;
 Cosmological evolution;
 Bayesian statistics;
 678;
 675;
 98;
 1611;
 336;
 1900;
 Astrophysics  High Energy Astrophysical Phenomena;
 General Relativity and Quantum Cosmology
 EPrint:
 8 pages main text + 3 page appendix, 7 figures. Updated to match accepted version