NEUTRON STARS VERSUS BLACK HOLES: PROBING THE MASS GAP WITH LIGO/VIRGO

Tyson B. Littenberg, Ben Farr, Scott Coughlin, Vicky Kalogera, Daniel E. Holz

Research output: Contribution to journalArticlepeer-review

39 Scopus citations

Abstract

Inspirals and mergers of black hole (BH) and/or neutron star (NS) binaries are expected to be abundant sources for ground-based gravitational-wave (GW) detectors. We assess the capabilities of Advanced LIGO and Virgo to measure component masses using inspiral waveform models including spin-precession effects using a large ensemble of GW sources randomly oriented and distributed uniformly in volume. For 1000 sources this yields signal-to-noise ratios between 7 and 200. We make quantitative predictions for how well LIGO and Virgo will distinguish between BHs and NSs and appraise the prospect of using LIGO/Virgo (LV) observations to definitively confirm, or reject, the existence of a putative "mass gap" between NSs (m ≤ 3 M⊙) and BHs (m ≥ 5 M⊙). We find sources with the smaller mass component satisfying m2 ≲ 1.5 M⊙ to be unambiguously identified as containing at least one NS, while systems with m2 ≳ 6 M⊙ will be confirmed binary BHs. Binary BHs with m2 < 5 M⊙ (i.e., in the gap) cannot generically be distinguished from NSBH binaries. High-mass NSs (2 < m < 3 M⊙) are often consistent with low-mass BHs (m < 5 M⊙), posing a challenge for determining the maximum NS mass from LV observations alone. Individual sources will seldom be measured well enough to confirm objects in the mass gap and statistical inferences drawn from the detected population will be strongly dependent on the underlying distribution. If nature happens to provide a mass distribution with the populations relatively cleanly separated in chirp mass space, as some population synthesis models suggest, then NSs and BHs will be more easily distinguishable.

Original languageEnglish (US)
Article numberL24
JournalAstrophysical Journal Letters
Volume807
Issue number2
DOIs
StatePublished - Jul 10 2015

Keywords

  • gravitational waves

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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