Observing Intermediatemass Black Holes and the Upper Stellarmass gap with LIGO and Virgo
Abstract
Using groundbased gravitationalwave detectors, we probe the mass function of intermediatemass black holes (IMBHs) wherein we also include BHs in the upper mass gap at ~60130 M _{⊙}. Employing the projected sensitivity of the upcoming LIGO and Virgo fourth observing run (O4), we perform Bayesian analysis on quasicircular nonprecessing, spinning IMBH binaries (IMBHBs) with total masses 50500 M _{⊙}, mass ratios 1.25, 4, and 10, and dimensionless spins up to 0.95, and estimate the precision with which the sourceframe parameters can be measured. We find that, at 2σ, the mass of the heavier component of IMBHBs can be constrained with an uncertainty of ~10%40% at a signaltonoise ratio of 20. Focusing on the stellarmass gap with new tabulations of the ^{12}C(α, γ)^{16}O reaction rate and its uncertainties, we evolve massive helium core stars using MESA to establish the lower and upper edges of the mass gap as ≃ ${59}_{13}^{+34}$ M _{⊙} and ≃ ${139}_{14}^{+30}$ M _{⊙} respectively, where the error bars give the mass range that follows from the ±3σ uncertainty in the ^{12}C(α, γ)^{16}O nuclear reaction rate. We find that high resolution of the tabulated reaction rate and fine temporal resolution are necessary to resolve the peak of the BH mass spectrum. We then study IMBHBs with components lying in the mass gap and show that the O4 run will be able to robustly identify most such systems. Finally, we reanalyze GW190521 with a stateoftheart alignedspin waveform model, finding that the primary mass lies in the mass gap with 90% credibility.
 Publication:

The Astrophysical Journal
 Pub Date:
 January 2022
 DOI:
 10.3847/15384357/ac3130
 arXiv:
 arXiv:2105.06366
 Bibcode:
 2022ApJ...924...39M
 Keywords:

 675;
 1043;
 678;
 General Relativity and Quantum Cosmology;
 Astrophysics  High Energy Astrophysical Phenomena
 EPrint:
 29 pages, 18 figures