The Fate of Neutron Star Binary Mergers

Journal Article · Tue Aug 01 00:00:00 EDT 2017 · Astrophysical Journal Letters

DOI:https://doi.org/10.3847/2041-8213/AA7F2F· OSTI ID:22654424

Piro, Anthony L. ^[1]; Giacomazzo, Bruno ^[2]; Perna, Rosalba ^[3]

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1. The Observatories of the Carnegie Institution for Science, 813 Santa Barbara Street, Pasadena, CA 91101 (United States)
2. Physics Department, University of Trento, via Sommarive 14, I-38123 Trento (Italy)
3. Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794 (United States)

Following merger, a neutron star (NS) binary can produce roughly one of three different outcomes: (1) a stable NS, (2) a black hole (BH), or (3) a supramassive, rotationally supported NS, which then collapses to a BH following angular momentum losses. Which of these fates occur and in what proportion has important implications for the electromagnetic transient associated with the mergers and the expected gravitational wave (GW) signatures, which in turn depend on the high density equation of state (EOS). Here we combine relativistic calculations of NS masses using realistic EOSs with Monte Carlo population synthesis based on the mass distribution of NS binaries in our Galaxy to predict the distribution of fates expected. For many EOSs, a significant fraction of the remnants are NSs or supramassive NSs. This lends support to scenarios in which a quickly spinning, highly magnetized NS may be powering an electromagnetic transient. This also indicates that it will be important for future GW observatories to focus on high frequencies to study the post-merger GW emission. Even in cases where individual GW events are too low in signal to noise to study the post merger signature in detail, the statistics of how many mergers produce NSs versus BHs can be compared with our work to constrain the EOS. To match short gamma-ray-burst (SGRB) X-ray afterglow statistics, we find that the stiffest EOSs are ruled out. Furthermore, many popular EOSs require a significant fraction of ∼60%–70% of SGRBs to be from NS–BH mergers rather than just binary NSs.

• OSTI ID: 22654424
• Journal Information: Astrophysical Journal Letters, Vol. 844, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
AFTERGLOW
ANGULAR MOMENTUM
BINARY ALLOY SYSTEMS
BLACK HOLES
COMPARATIVE EVALUATIONS
COSMIC GAMMA BURSTS
DENSITY
EMISSION
EQUATIONS OF STATE
GALAXIES
GAMMA RADIATION
GRAVITATIONAL WAVES
MASS
MASS DISTRIBUTION
MONTE CARLO METHOD
NEUTRON STARS
RELATIVISTIC RANGE
SYNTHESIS
X RADIATION