The DBL Survey I: discovery of 34 double-lined double white dwarf binaries

James Munday; Ingrid Pelisoli; P. E. Tremblay; T. R. Marsh; Gijs Nelemans; Antoine Bédard; Silvia Toonen; Elmé Breedt; Tim Cunningham; Mairi W. O'Brien; Harry Dawson

arXiv · 2407.02594

The DBL Survey I: discovery of 34 double-lined double white dwarf binaries

James Munday·Ingrid Pelisoli·P. E. Tremblay·T. R. Marsh·Gijs Nelemans·Antoine Bédard·Silvia Toonen·Elmé Breedt·Tim Cunningham·Mairi W. O'Brien·Harry Dawson

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Abstract

We present the first discoveries of the double-lined double white dwarf (DBL) survey that targets over-luminous sources with respect to the canonical white dwarf cooling sequence according to a set of well-defined criteria. The primary goal of the DBL survey is to identify compact double white dwarf binary star systems from a unique spectral detection of both stars, which then enables a precise quantification of the atmospheric parameters and radial velocity variability of a system. Our search of 117 candidates that were randomly selected from a magnitude limited sample of 399 yielded a 29% detection efficiency with 34 systems exhibiting a double-lined signature. A further 38 systems show strong evidence of being single-lined or potentially-double-lined double white dwarf binaries and 7 single-lined sources from the full observed sample are radial velocity variable. The 45 remaining candidates appear as a single WD with no companion or a non-DA white dwarf, bringing the efficiency of detecting binaries to 62%. Atmospheric fitting of all double-lined systems reveals a large fraction that have two similar mass components that combine to a total mass of 1.0-1.3 solar masses - a class of double white dwarf binaries that may undergo a sub-Chandrasekhar mass type Ia detonation or merge to form a massive O/Ne WD, although orbital periods are required to infer on which timescales. One double-lined system located 49pc away, WDJ181058.67+311940.94, is super-Chandrasekhar mass, making it the second such double white dwarf binary to be discovered.

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James Munday, Ingrid Pelisoli, P. E. Tremblay, T. R. Marsh, Gijs Nelemans, Antoine Bédard, Silvia Toonen, Elmé Breedt, Tim Cunningham, Mairi W. O'Brien, Harry Dawson. 2025-05-16. The DBL Survey I: discovery of 34 double-lined double white dwarf binaries. https://arxiv.org/abs/2407.02594

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