A Common Origin for Low Mass Ratio Events Observed by LIGO and Virgo in the First Half of the Third Observing Run

Abstract

In its third observing run, the LIGO/Virgo collaboration has announced a potential neutron star-black hole (NSBH) merger candidate, GW190426_152155. Together with GW190814, these two events belong to a class of binaries with a secondary mass less than $3M_{\odot }$. While the secondary system in GW190426_152155 is consistent with being a neutron star with a mass of $1.5_{-0.5}^{+0.8}{M}_{\odot }$, that of GW190814 is a $2.59_{-0.09}^{+0.08}{M}_{\odot }$ object and counts as the first confirmed detection of a mass-gap object. Here we argue that these two events could have a common origin as follows: both are formed as NSBH systems; however, the larger escape velocity of a system with more massive primary BH increases the bound fraction of the ejecta material from the supernova explosion leading to the formation of a NS. This bound material forms a disk, which is preferentially accreted onto the NS. This scenario predicts the secondary component mass should correlate with the primary component mass, which is consistent with GW190426_152155 and GW190814. If this hypothesis is corroborated by upcoming observations, GW190814-like events can be excluded from the binary black hole population when inferring their global characteristics.

Accepted for publication at ApJ Letters

References in corpus (17)

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• Advanced LIGO
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• Formation and merging of Mass Gap Black Holes in Gravitational Wave Merger Events from Wide Hierarchical Quadruple Systems
• Does GW190425 require an alternative formation pathway than a fast-merging channel?
• Formation of mass gap objects in highly asymmetric mergers
• Formation of mass gap compact object and black hole binary from Population III stars

Cited by in corpus (4)

• GWTC-2.1: Deep Extended Catalog of Compact Binary Coalescences Observed by LIGO and Virgo During the First Half of the Third Observing Run
• Divergence in mass ratio distributions between low-mass and high-mass coalescing binary black holes
• Population properties of neutron stars in the coalescing compact binaries
• Black Hole Gravitational Potential Enhanced Fallback Accretion onto the Nascent Lighter Compact Object: Tentative Evidence in the O3 Run Data of LIGO/Virgo