The binary fraction, separation distribution, and merger rate of white dwarfs from SPY

Abstract

From a sample of spectra of 439 white dwarfs (WDs) from the ESO-VLT Supernova-Ia Progenitor surveY (SPY), we measure the maximal changes in radial-velocity (DRVmax) between epochs (generally two epochs, separated by up to 470d), and model the observed DRVmax statistics via Monte-Carlo simulations, to constrain the population characteristics of double WDs (DWDs). The DWD fraction among WDs is fbin=0.100+/-0.020 (1-sigma, random) +0.02 (systematic), in the separation range ~<4AU within which the data are sensitive to binarity. Assuming the distribution of binary separation, a, is a power-law, dN/da ~ a^alpha, at the end of the last common-envelope phase and the start of solely gravitational-wave-driven binary evolution, the constraint by the data is alpha=-1.3+/-0.2 (1-sigma) +/-0.2 (systematic). If these parameters extend to small separations, the implied Galactic WD merger rate per unit stellar mass is R_merge=(1-80)e-13 /yr/Msun (2-sigma), with a likelihood-weighted mean of R_merge=(7+/-2)e-13 /yr/Msun (1-sigma). The Milky Way's specific Type-Ia supernova (SN Ia) rate is likely R_Ia~1.1e-13 /yr/Msun and therefore, in terms of rates, a possibly small fraction of all merging DWDs (e.g. those with massive-enough primary WDs) could suffice to produce most or all SNe Ia.

MNRAS, in press

References in corpus (10)

• The UKIRT Infrared Deep Sky Survey (UKIDSS)
• The frequency of planetary debris around young white dwarfs
• White Dwarf Mass Distribution in the SDSS
• New white dwarf stars in the Sloan Digital Sky Survey Data Release 10
• A Deep Proper Motion Catalog Within the Sloan Digital Sky Survey Footprint. II. The White Dwarf Luminosity Function
• The origin of single low-mass WDs: another problem that consequential angular momentum loss in CVs might solve
• The Way To a Double Degenerate: $\sim 15-20$ per cent of $1M_{\odot }\le M\le 8M_{\odot }$ Stars have a $M>1M_{\odot }$ Companion
• Common envelope: the progress and the pitfalls
• The search for progenitor models of type Ia supernovae
• Double degenerates from the supernova Ia progenitor survey (SPY)

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• A Gemini Snapshot Survey for Double Degenerates
• Periodic optical variability and debris accretion in white dwarfs: a test for a causal connection
• On the optical transients from double white-dwarf mergers
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• HighSpec: A High-Resolution Spectrograph for the MAST Telescope Array
• MAUVE: An Ultraviolet Astrophysics Probe Mission Concept