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Mass transfer in white dwarf-neutron star binaries

Bobrick, Alexey LU orcid ; Davies, Melvyn B. LU and Church, Ross P. LU orcid (2017) In Monthly Notices of the Royal Astronomical Society 467(3). p.3556-3575
Abstract
We perform hydrodynamic simulations of mass transfer in binaries that contain a white dwarf and a neutron star (WD-NS binaries), and measure the specific angular momentum of material lost from the binary in disc winds. By incorporating our results within a long-term evolution model, we measure the long-term stability of mass transfer in these binaries. We find that only binaries containing helium white dwarfs (WDs) with masses less than a critical mass of M-WD, (crit) = 0.2 M-circle dot undergo stable mass transfer and evolve into ultracompact X-ray binaries. Systems with higher mass WDs experience unstable mass transfer, which leads to tidal disruption of the WD. Our low critical mass compared to the standard jet-only model of mass-loss... (More)
We perform hydrodynamic simulations of mass transfer in binaries that contain a white dwarf and a neutron star (WD-NS binaries), and measure the specific angular momentum of material lost from the binary in disc winds. By incorporating our results within a long-term evolution model, we measure the long-term stability of mass transfer in these binaries. We find that only binaries containing helium white dwarfs (WDs) with masses less than a critical mass of M-WD, (crit) = 0.2 M-circle dot undergo stable mass transfer and evolve into ultracompact X-ray binaries. Systems with higher mass WDs experience unstable mass transfer, which leads to tidal disruption of the WD. Our low critical mass compared to the standard jet-only model of mass-loss arises from the efficient removal of angular momentum in the mechanical disc winds, which develop at highly super-Eddington mass-transfer rates. We find that the eccentricities expected for WD-NS binaries when they come into contact do not affect the loss of angular momentum, and can only affect the long-term evolution if they change on shorter time-scales than the mass-transfer rate. Our results are broadly consistent with the observed numbers of both ultracompact X-ray binaries and radio pulsars with WD companions. The observed calcium-rich gap transients are consistent with the merger rate of unstable systems with higher mass WDs. (Less)
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author
; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
hydrodynamics, methods: numerical, binaries: close, stars: neutron, white dwarfs
in
Monthly Notices of the Royal Astronomical Society
volume
467
issue
3
pages
20 pages
publisher
Oxford University Press
external identifiers
  • scopus:85039170078
ISSN
0035-8711
DOI
10.1093/mnras/stx312
project
Interacting Giants and Compact Stars
language
English
LU publication?
yes
id
9f4d026e-425e-41e7-8dfa-8f8b2abfccff
date added to LUP
2018-09-27 19:58:52
date last changed
2025-10-14 13:25:43
@article{9f4d026e-425e-41e7-8dfa-8f8b2abfccff,
  abstract     = {{We perform hydrodynamic simulations of mass transfer in binaries that contain a white dwarf and a neutron star (WD-NS binaries), and measure the specific angular momentum of material lost from the binary in disc winds. By incorporating our results within a long-term evolution model, we measure the long-term stability of mass transfer in these binaries. We find that only binaries containing helium white dwarfs (WDs) with masses less than a critical mass of M-WD, (crit) = 0.2 M-circle dot undergo stable mass transfer and evolve into ultracompact X-ray binaries. Systems with higher mass WDs experience unstable mass transfer, which leads to tidal disruption of the WD. Our low critical mass compared to the standard jet-only model of mass-loss arises from the efficient removal of angular momentum in the mechanical disc winds, which develop at highly super-Eddington mass-transfer rates. We find that the eccentricities expected for WD-NS binaries when they come into contact do not affect the loss of angular momentum, and can only affect the long-term evolution if they change on shorter time-scales than the mass-transfer rate. Our results are broadly consistent with the observed numbers of both ultracompact X-ray binaries and radio pulsars with WD companions. The observed calcium-rich gap transients are consistent with the merger rate of unstable systems with higher mass WDs.}},
  author       = {{Bobrick, Alexey and Davies, Melvyn B. and Church, Ross P.}},
  issn         = {{0035-8711}},
  keywords     = {{hydrodynamics; methods: numerical; binaries: close; stars: neutron; white dwarfs}},
  language     = {{eng}},
  month        = {{06}},
  number       = {{3}},
  pages        = {{3556--3575}},
  publisher    = {{Oxford University Press}},
  series       = {{Monthly Notices of the Royal Astronomical Society}},
  title        = {{Mass transfer in white dwarf-neutron star binaries}},
  url          = {{http://dx.doi.org/10.1093/mnras/stx312}},
  doi          = {{10.1093/mnras/stx312}},
  volume       = {{467}},
  year         = {{2017}},
}