A source of high-velocity white dwarfs

Abstract

We investigate whether the recently-observed population of high-velocity white dwarfs can be derived from a population of binaries residing initially within the thin disk of the Galaxy. In particular we consider binaries where the primary is sufficiently massive to explode as a type II supernova. A large fraction of such binaries are broken up when the primary then explodes as a supernova owing to the combined effects of the mass loss from the primary and the kick received by the neutron star on its formation. For binaries where the primary evolves to fill its Roche lobe, mass transfer from the primary leads to the onset of a common envelope phase during which the secondary and the core of the primary spiral together as the envelope is ejected. Such binaries are the progenitors of X-ray binaries if they are not broken up when the primary explodes. For those systems which are broken up, a large number of the secondaries receive kick velocities ~100 - 200 km/s and subsequently evolve into white dwarfs. We compute trajectories within the Galactic potential for this population of stars and relate the birthrate of these stars over the entire Galaxy to those seen locally with high velocities relative to the LSR. We show that for a reasonable set of assumptions concerning the Galactic supernova rate and the binary population, our model produces a local number density of high-velocity white dwarfs compatible with that inferred from observations. We therefore propose that a population of white dwarfs originating in the thin disk may make a significant contribution to the observed population of high-velocity white dwarfs.

6 pages, 5 figures; revised version, MNRAS in press

References in corpus (3)

• Direct Detection of Galactic Halo Dark Matter
• High-velocity white dwarfs: thick disk, not dark matter
• Halo White Dwarfs, Thick Disks and a Sanity Check

Cited by in corpus (16)

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• MMT Hypervelocity Star Survey
• 3D kinematics of white dwarfs from the SPY project
• Hypervelocity Stars III. The Space Density and Ejection History of Main Sequence Stars from the Galactic Center
• Hypervelocity Stars II. The Bound Population
• MMT Hypervelocity Star Survey. II. Five New Unbound Stars
• The Anisotropic Spatial Distribution of Hypervelocity Stars
• Runaway Stars, Hypervelocity Stars, and Radial Velocity Surveys
• Type Ia Supernovae and High Velocity White Dwarfs
• The galactic population of white dwarfs
• A Critical Examination of Halo White Dwarf Candidates
• Ages of White Dwarf-Red Subdwarf Systems
• Trigonometric parallaxes of high velocity halo white dwarf candidates
• Discovery of a nearby halo white dwarf with proper motion mu=2.55 arcsec/yr
• The Mass and Age Distribution of Halo White Dwarfs in the Canada-France Imaging Survey
• Microlensing signature of a white dwarf population in the galactic halo