Evidence for reduced magnetic braking in polars from binary population models

Abstract

We present the first population synthesis of synchronous magnetic cataclysmic variables, called polars, taking into account the effect of the white dwarf (WD) magnetic field on angular momentum loss. We implemented the reduced magnetic braking (MB) model proposed by Li, Wu & Wickramasinghe into the Binary Stellar Evolution (BSE) code recently calibrated for cataclysmic variable (CV) evolution. We then compared separately our predictions for polars and non-magnetic CVs with a large and homogeneous sample of observed CVs from the Sloan Digital Sky Survey. We found that the predicted orbital period distributions and space densities agree with the observations if period bouncers are excluded. For polars, we also find agreement between predicted and observed mass transfer rates, while the mass transfer rates of non-magnetic CVs with periods $\gtrsim 3$ hr drastically disagree with those derived from observations. Our results provide strong evidence that the reduced MB model for the evolution of highly magnetized accreting WDs can explain the observed properties of polars. The remaining main issues in our understanding of CV evolution are the origin of the large number of highly magnetic WDs, the large scatter of the observed mass transfer rates for non-magnetic systems with periods $\gtrsim 3$ hr, and the absence of period bouncers in observed samples.

15 pages, accepted for publication in MNRAS

References in corpus (45)

• The Gaia mission
• The Catalina Surveys Periodic Variable Star Catalog
• Magnetic White Dwarfs
• The Donor Stars of Cataclysmic Variables
• Post-common-envelope binaries from SDSS. IX: Constraining the common-envelope efficiency
• Binary Star Origin of High Field Magnetic White Dwarfs
• Spectropolarimetric Survey of Hydrogen-rich White Dwarf Stars
• The Ages of the Thin Disk, Thick Disk, and the Halo from Nearby White Dwarfs
• On the evolutionary status of short period cataclysmic variables
• On the magnetic topology of partially and fully convective stars
• Population Synthesis of Cataclysmic Variables: I. Inclusion of Detailed Nuclear Evolution
• Monte Carlo simulations of post-common-envelope white dwarf + main sequence binaries: comparison with the SDSS DR7 observed sample
• A common origin of magnetism from planets to white dwarfs
• Effective Temperatures of Cataclysmic Variable White Dwarfs as a Probe of their Evolution
• SW Sextantis stars: the dominant population of CVs with orbital periods between 3-4 hours
• A brown dwarf mass donor in an accreting binary
• The evolutionary status of Cataclysmic Variables: Eclipse modelling of 15 systems
• Evolution of Cataclysmic Variables and Related Binaries Containing a White-Dwarf
• One thousand cataclysmic variables from the Catalina Real-time Transient Survey
• VLT/FORS spectroscopy of faint cataclysmic variables discovered by the Sloan Digital Sky Survey
• How Many CVs are Crossing the Period Gap? A Test for the Disruption of Magnetic Braking
• Spectroscopic search for new SW Sextantis stars in the 3-4 hour orbital period range -- I
• The nature of the close magnetic white dwarf + probable brown dwarf binary SDSS J121209.31+013627.7
• The chemical evolution of galaxies with a variable IGIMF
• The population of white dwarf-main sequence binaries in the SDSS DR 12
• Dwarf novae in the Hamburg Quasar Survey: Rarer than expected
• Hunting For Eclipses: High Speed Observations of Cataclysmic Variables
• The origin of single low-mass WDs: another problem that consequential angular momentum loss in CVs might solve
• SDSS J233325.92+152222.1 and the evolution of intermediate polars
• A Trip to the Cataclysmic Binary Zoo: Detailed Follow-Up of 35 Recently-Discovered Systems
• The serendipituous discovery of a short-period eclipsing polar in 2XMMp
• Cyclic brightening in the short-period WZ Sge-type cataclysmic variable SDSS J080434.20+510349.2
• XMM-Newton observations of the complex spin pulse of the intermediate polar PQ~Geminorum
• Followup Observations of SDSS and CRTS Candidate Cataclysmic Variables
• Evidence for mass accretion driven by spiral shocks onto the white dwarf in SDSS J123813.73-033933.0
• SDSSJ001153.08-064739.2, a cataclysmic variable with an evolved donor in the period gap
• Orbital periods of cataclysmic variables identified by the SDSS. V. VLT, NTT and Magellan observations of nine equatorial systems
• Spectroscopic Orbital Periods for 29 Cataclysmic Variables from the Sloan Digital Sky Survey
• Orbital periods of cataclysmic variables identified by the SDSS. IX. NTT photometry of eight eclipsing and three magnetic systems
• Orbital periods of cataclysmic variables identified by the SDSS. IV. SDSS J220553.98+115553.7 has stopped pulsating
• The Space Density of Post-Period Minimum Cataclysmic Variables
• XMM-Newton and Optical Observations of Cataclysmic Variables from SDSS
• Curious Variables Experiment (CURVE). CCD photometry of active dwarf nova DI UMa
• Photometry of the SW Sex-type nova-like BH Lyncis in high state
• Time-Resolved Photometry of the Optical Counterpart of Swift J2319.4+2619

Cited by in corpus (13)

• Formation of millisecond pulsars with helium white dwarfs, ultra-compact X-ray binaries and gravitational wave sources
• Magnetic braking saturates: evidence from the orbital period distribution of low-mass detached eclipsing binaries from ZTF
• Magnetic white dwarfs in post-common-envelope binaries
• The cataclysmic variable orbital period gap: More evident than ever
• Galactic Model Parameters and Space Density of Cataclysmic Variables in Gaia Era: New Constraints to Population Models
• Period bouncers as detached magnetic cataclysmic variables
• Are white dwarf magnetic fields in close binaries generated during common-envelope evolution?
• Long-term photometric monitoring and spectroscopy of the white dwarf pulsar AR Scorpii
• A Joint SRG/eROSITA + ZTF Search: Discovery of a 97-min Period Eclipsing Cataclysmic Variable with Evidence of a Brown Dwarf Secondary
• Life after eruption VIII: The orbital periods of novae
• X-ray and ultraviolet observations of the eclipsing cataclysmic variables OV Bootis and SDSS J103533.02+055158.3 with degenerate donors
• Search for magnetic accretion in SW Sextantis systems
• First Detailed Analysis of a Relatively Deep, Low Mass-ratio Contact Binary: ATO J108.6991+27.8306