Find the Gap: Black Hole Population Analysis with an Astrophysically Motivated Mass Function

TL;DR

This paper introduces a new astrophysically motivated black hole mass function, analyzes LIGO-Virgo data, and finds evidence for a mass gap edge consistent with stellar theory, with implications for physics beyond standard models.

Contribution

The paper develops a novel black hole mass function incorporating star formation and supernova physics, and applies it to gravitational wave data to identify the black hole mass gap edge.

Findings

Detection of a peak at ~75 solar masses in the mass function.

Identification of the black hole mass gap edge at ~55 solar masses.

The new mass function fits observational data as well as existing models.

Abstract

We introduce a novel black hole mass function which realistically models the physics of star formation and pair instability supernova with a minimal number of parameters. Applying this to all events in the LIGO-Virgo GWTC-2 catalog, we detect a peak at M_BHMG = 74.8^{+4.3}_{-8.0} MS, followed by a break in the mass function. Repeating the analysis without the black holes from the event GW190521, we find this feature at M_BHMG = 55.4^{+3.0}_{-6.1} MS. The latter result establishes the edge of the anticipated "black hole mass gap" at a value compatible with the expectation from standard stellar structure theory, while the former result is ~ 20MS higher, which would have far-reaching implications if confirmed. Using Bayesian techniques, we establish that our mass function fits a new catalog of black hole masses approximately as well as the pre-existing phenomenological mass functions. We also remark on the implications of these results for constraining or discovering new phenomena in nuclear and particle physics.