Fallback Supernova Assembly of Heavy Binary Neutron Stars and Light Black Hole–Neutron Star Pairs and the Common Stellar Ancestry of GW190425 and GW200115

The detection of the unusually heavy binary neutron star merger GW190425 marked a stark contrast to the mass distribution from known Galactic pulsars in double neutron star binaries and gravitational-wave source GW170817. We suggest here a formation channel for heavy binary neutron stars and light b...

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Bibliographic Details
Published in:Astrophysical journal. Letters 2021-10, Vol.920 (1), p.L17
Main Authors: Vigna-Gómez, Alejandro, Schrøder, Sophie L., Ramirez-Ruiz, Enrico, Aguilera-Dena, David R., Batta, Aldo, Langer, Norbert, Willcox, Reinhold
Format: Article
Language:English
Subjects:
Assembly
Binary stars
Black holes
Compact objects
Companion stars
Deposition
Galaxies
Gravitational wave astronomy
Gravitational wave sources
Gravitational waves
Helium
Hydrogen
Mass distribution
Mass transfer
Massive stars
Milky Way
Neutron stars
Neutrons
Pulsars
Star mergers
Stars
Stellar evolution
Stellar remnants
Stellar systems
Supernova
Supernovae
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Summary:The detection of the unusually heavy binary neutron star merger GW190425 marked a stark contrast to the mass distribution from known Galactic pulsars in double neutron star binaries and gravitational-wave source GW170817. We suggest here a formation channel for heavy binary neutron stars and light black hole–neutron star binaries in which massive helium stars, which had their hydrogen envelope removed during a common-envelope phase, remain compact and avoid mass transfer onto the neutron star companion, possibly avoiding pulsar recycling. We present three-dimensional simulations of the supernova explosion of the massive stripped helium star and follow the mass fallback evolution and the subsequent accretion onto the neutron star companion. We find that fallback leads to significant mass growth in the newly formed neutron star. This can explain the formation of heavy binary neutron star systems such as GW190425, as well as predict the assembly of light black hole–neutron star systems such as GW200115. This formation avenue is consistent with the observed mass–eccentricity correlation of binary neutron stars in the Milky Way. Finally, avoiding mass transfer suggests an unusually long spin-period population of pulsar binaries in our Galaxy.
ISSN:2041-8205
2041-8213
DOI:10.3847/2041-8213/ac2903