DA white dwarfs from the LSS-GAC survey DR1: the preliminary luminosity and mass functions and formation rate

Abstract

Modern large-scale surveys have allowed the identification of large numbers of white dwarfs. However, these surveys are subject to complicated target selection algorithms, which make it almost impossible to quantify to what extent the observational biases affect the observed populations. The LAMOST (Large Sky Area Multi-Object Fiber Spectroscopic Telescope) Spectroscopic Survey of the Galactic anti-center (LSS-GAC) follows a well-defined set of criteria for selecting targets for observations. This advantage over previous surveys has been fully exploited here to identify a small yet well-characterised magnitude-limited sample of hydrogen-rich (DA) white dwarfs. We derive preliminary LSS-GAC DA white dwarf luminosity and mass functions. The space density and average formation rate of DA white dwarfs we derive are 0.83+/-0.16 x 10^{-3} pc^{-3} and 5.42 +/- 0.08 x 10^{-13} pc^{-3} yr^{-1}, respectively. Additionally, using an existing Monte Carlo population synthesis code we simulate the population of single DA white dwarfs in the Galactic anti-center, under various assumptions. The synthetic populations are passed through the LSS-GAC selection criteria, taking into account all possible observational biases. This allows us to perform a meaningful comparison of the observed and simulated distributions. We find that the LSS-GAC set of criteria is highly efficient in selecting white dwarfs for spectroscopic observations (80-85 per cent) and that, overall, our simulations reproduce well the observed luminosity function. However, they fail at reproducing an excess of massive white dwarfs present in the observed mass function. A plausible explanation for this is that a sizable fraction of massive white dwarfs in the Galaxy are the product of white dwarf-white dwarf mergers.

23 pages, 14 figures and 5 tables. Accepted for publication by MNRAS

References in corpus (14)

• New constraints on the chemical evolution of the solar neighbourhood and Galactic disc(s). Improved astrophysical parameters for the Geneva-Copenhagen Survey
• Empirical Color Transformations Between SDSS Photometry and Other Photometric Systems
• White Dwarf Mass Distribution in the SDSS
• New white dwarf stars in the Sloan Digital Sky Survey Data Release 10
• The initial-final mass relationship of white dwarfs revisited: effect on the luminosity function and mass distribution
• Post Common Envelope Binaries from SDSS. I: 101 white dwarf main sequence binaries with multiple SDSS spectroscopy
• LAMOST Spectroscopic Survey of the Galactic Anti-centre (LSS-GAC): target selection and the first release of value-added catalogues
• The chemical diversity of exo-terrestrial planetary debris around white dwarfs
• White Dwarf Luminosity and Mass Functions from Sloan Digital Sky Survey Spectra
• A three dimensional extinction map of the Galactic Anticentre from multi-band photometry
• White dwarf-main sequence binaries from LAMOST: the DR1 catalogue
• Relative Flux Calibration of the LAMOST Spectroscopic Survey of the Galactic Anti-center
• The mass and luminosity functions and the formation rate of DA white dwarfs in the Sloan Digital Sky Survey
• The effects of metallicity on the Galactic disk population of white dwarfs

Cited by in corpus (7)

• LAMOST Spectroscopic Survey of the Galactic Anticentre (LSS-GAC): the second release of value-added catalogues
• The white dwarf luminosity function
• An independent test of the photometric selection of white dwarf candidates using LAMOST DR3
• Chemically peculiar A and F stars with enhanced s-process and iron-peak elements: stellar radiative acceleration at work
• J-PLUS: Tools to identify compact planetary nebulae in the Javalambre and southern photometric local universe surveys
• New ZZ Ceti stars from the LAMOST survey
• The effects of unresolved double-degenerates in the white dwarf luminosity function