Black holes in the low-mass gap: Implications for gravitational-wave observations

Research output: Contribution to journalArticlepeer-review


  • Anuradha Gupta
  • K. G. Arun
  • Emanuele Berti
  • B. S. Sathyaprakash

Colleges, School and Institutes


Binary neutron-star mergers will predominantly produce black-hole remnants of mass ∼3 - 4 M , thus populating the putative low-mass gap between neutron stars and stellar-mass black holes. If these low-mass black holes are in dense astrophysical environments, mass segregation could lead to "second-generation" compact binaries merging within a Hubble time. In this paper, we investigate possible signatures of such low-mass compact binary mergers in gravitational-wave observations. We show that this unique population of objects, if present, will be uncovered by the third-generation gravitational-wave detectors, such as Cosmic Explorer and Einstein Telescope. Future joint measurements of chirp mass M and effective spin χeff could clarify the formation scenario of compact objects in the low-mass gap. As a case study, we show that the recent detection of GW190425 (along with GW170817) favors a double Gaussian mass model for neutron stars, under the assumption that the primary in GW190425 is a black hole formed from a previous binary neutron-star merger....


Original languageUndefined/Unknown
JournalPhysical Review D
Publication statusPublished - May 2020