SDSS unveils a population of intrinsically faint cataclysmic variables at the minimum orbital period

By B. Gänsicke, M. Dillon, J. Southworth, J. Thorstensen, P. Rodríguez-Gil, A. Aungwerojwit, T. Marsh, P. Szkody, S. Barros, J. Casares and 8 more. 2009

208 citations recorded by the source corpus.

We discuss the properties of 137 cataclysmic variables (CVs) which are included in the Sloan Digital Sky Survey (SDSS) spectroscopic data base, and for which accurate orbital periods have been measured. 92 of these systems are new discoveries from SDSS and were followed-up in more detail over the past few years. 45 systems were previously identified as CVs because of the detection of optical outbursts and/or X-ray emission, and subsequently re-identified from the SDSS spectroscopy. The period distribution of the SDSS CVs differs dramatically from that of all the previously known CVs, in particular it contains a significant accumulation of systems in the orbital period range 80-86 min. We identify this feature as the elusive 'period minimum spike' predicted by CV population models, which resolves a long-standing discrepancy between compact binary evolution theory and observations. We show that this spike is almost entirely due to the large number of CVs with very low accretion activity identified by SDSS. The optical spectra of these systems are dominated by emission from the white dwarf photosphere, and display little or no spectroscopic signature from the donor stars, suggesting very low mass companion stars. We determine the average absolute magnitude of these low-luminosity CVs at the period minimum to be > = 11.6 +/- 0.7. Comparison of the SDSS CV sample to the CVs found in the Hamburg Quasar Survey and the Palomar Green Survey suggests that the depth of SDSS is the key ingredient resulting in the discovery of a large number of intrinsically faint short-period systems.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/16f146d3f5adff853d0d3d996abf723a5432dadc

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In Astronomy and Astrophysics

Citations in the corpus

MODULES FOR EXPERIMENTS IN STELLAR ASTROPHYSICS (MESA) (2010, background): “These short orbital period ( P orb < 2 hr) cataclysmic variables are the end points of these mass transferring systems (Patterson 1998; Kolb & Baraffe 1999) and are now being discovered in large numbers in the SDSS database (more than 100 studied by G¨ansicke et al. 2009).”
Magnetic White Dwarfs (2015, background): “The discrepancy between observations and theory has been a major issue for a long time and only recently mitigated by deep optical surveys, such as the SDSS which has unveiled the long-sought low accretion rate and short orbital period CVs (Gänsicke et al. 2009, see their Fig.”
MODULES FOR EXPERIMENTS IN STELLAR ASTROPHYSICS (MESA): BINARIES, PULSATIONS, AND EXPLOSIONS (2015, background): “Period Gap of Cataclysmic Variables Although cataclysmic variables (CVs) span a wide range of periods, observations show a lack of systems in the range 2 h < Porb < 3 h (see, for instance, Gänsicke et al. 2009).”
Post common envelope binaries from SDSS - XI. The white dwarf mass distributions of CVs and pre-CVs (2011, background): “…Digital Sky Survey (SDSS Adelman-McCarthy et al. 2008; Abazajian et al. 2009), we now have a large, homogeneous sample of faint (i ≤ 19.1) CVs (Szkody et al. 2009, and references therein) that contains a substantial number of short-period CVs accreting at very low rates (Gänsicke et al. 2009).”
X-Ray Emissions from Accreting White Dwarfs: A Review (2017, background): “…this sample is biased towards optically bright CVs. Non-magnetic CV population probably is dominated by the very faint population discovered with Sloan Digital Sky Survey (SDSS), which are thought mostly to be WZ Sge type dwarf novae with extremely long recurrence types (Gänsicke et al. 2009).”