Hard X-ray luminosity functions of cataclysmic variables: Joint Swift/BAT and Gaia data

Abstract

Cataclysmic variables (CVs) are the most numerous population among the Galactic objects emitting in hard X-rays. Most probably, they are responsible for the extended hard X-ray emission of the Galactic ridge and the central Galactic regions. Here we consider the sample of CVs detected in the all-sky hard X-ray Swift/BAT survey which were also detected by Gaia and thus have reliable distance estimates. Using these data, we derive accurate estimates for local number density per solar mass (${\rho }_M=1.37_{-0.16}^{+0.3}\times 10^{-5}{M}_{\odot }^{-1}$) and luminosity density per solar mass (${\rho }_L=8.95_{-0.1}^{+0.15}\times 10^{26}erg{s}^{-1}{M}_{\odot }^{-1}$) for objects in the sample. These values appear to be in good agreement with the integrated Galactic ridge X-ray emission and Nuclear Stellar Cluster luminosities. Analysis of the differential luminosity functions $d{\rho }_M/d({\log }_{10}{L}_x)$ and $d{\rho }_L/d({\log }_{10}{L}_x)$ confirms that there are two populations of hard X-ray emitting CVs. Intermediate polars dominate at luminosities $L>10^{33}erg{s}^{-1}$, whereas non-magnetic CVs and polars are much more numerous but have lower luminosities on average. As a consequence, the contribution of these populations to the observed hard X-ray luminosity is almost equivalent.

arXiv comment10 pages, 4 figures, 4 tables. Published in MNRAS in 2022. A typo in Eq. (3) has been corrected

References in corpus (54)

• emcee: The MCMC Hammer
• Estimating distances from parallaxes. V: Geometric and photogeometric distances to 1.47 billion stars in Gaia Early Data Release 3
• The Milky Way Tomography with SDSS: I. Stellar Number Density Distribution
• Mass models of the Milky Way
• Catalogue of cataclysmic binaries, low-mass X-ray binaries and related objects (Seventh edition)
• The 105 month Swift-BAT all-sky hard X-ray survey
• The Milky Way in X-rays for an outside observer: Log(N)-Log(S) and Luminosity Function of X-ray binaries from RXTE/ASM data
• The Milky Way total mass profile as inferred from Gaia DR2
• X-ray Emissions from Accreting White Dwarfs: a Review
• Parallax Systematics and Photocenter Motions of Benchmark Eclipsing Binaries in Gaia EDR3
• A Volume Limited Sample of Cataclysmic Variables from $Gaia$ DR2: Space Density and Population Properties
• INTEGRAL/IBIS all-sky survey in hard X-rays
• X-ray luminosity function of faint point sources in the Milky Way
• Formation and evolution of compact binaries in globular clusters: I.Binaries with white dwarfs
• Unveiling the nature of INTEGRAL objects through optical spectroscopy. V. Identification and properties of 21 southern hard X-ray sources
• X-ray follow-ups of XSSJ12270-4859: a low-mass X-ray binary with gamma ray FERMI-LAT association
• RXTE broadband X-ray spectra of intermediate polars and white dwarf mass estimates
• The census of cataclysmic variables in the ROSAT Bright Survey
• Hard X-ray view on intermediate polars in the Gaia era
• Unveiling the nature of INTEGRAL objects through optical spectroscopy. VIII. Identification of 44 newly detected hard X-ray sources
• Constraints on the space density of intermediate polars from the Swift-BAT survey
• Characterization of new hard X-ray Cataclysmic Variables
• The space density and X-ray luminosity function of non-magnetic cataclysmic variables
• Evidence for intermediate polars as the origin of the Galactic Center hard X-ray emission
• The space density of cataclysmic variables: constraints from the ROSAT North Ecliptic Pole Survey
• Unveiling the nature of INTEGRAL objects through optical spectroscopy. X. A new multi-year, multi-observatory campaign
• Properties of the Galactic population of cataclysmic variables in hard X-rays
• MOCCA-SURVEY database I. Accreting white dwarf binary systems in globular clusters -- IV. cataclysmic variables -- properties of bright and faint populations
• Hard X-ray Cataclysmic Variables
• Polarized QPOs from the INTEGRAL polar IGRJ14536-5522 (=Swift J1453.4-5524)
• INTEGRAL/IBIS 17-yr hard X-ray all-sky survey
• Measuring the masses of magnetic white dwarfs: A NuSTAR Legacy Survey
• On the Correlated X-ray and Optical Evolution of SS Cygni
• The MAVERIC Survey: Chandra/ACIS Catalog of Faint X-ray sources in 38 Galactic globular clusters
• Models for the 3-D axisymmetric gravitational potential of the Milky Way Galaxy - A detailed modelling of the Galactic disk
• Broad-band characteristics of seven new hard X-ray selected cataclysmic variables
• Cataclysmic variable evolution and the white dwarf mass problem: A Review
• Optical Studies of 15 Hard X-ray Selected Cataclysmic Binaries
• On the nature of the hard X-ray sources SWIFTJ1907.3-2050, IGRJ12123-5802 and IGRJ19552+0044
• Optical and X-ray Studies of Ten X-ray Selected Cataclysmic Binaries
• IGR J19552+0044: A new asynchronous short period polar: "Filling the gap between intermediate and ordinary polars"
• On the space density of X-ray selected cataclysmic variables
• The nuclear star cluster and nuclear stellar disc of the Milky Way: Different stellar population and star formation history
• Optical Studies of Thirteen Hard X-ray Selected Cataclysmic Binaries from the Swift-BAT Survey
• Accurate classification of 29 objects detected in the 39 months Palermo Swift/BAT hard X-ray catalogue
• Modelling the Milky Way. I -- Method and first results fitting the thick disk and halo with DES-Y3 data
• Chandra Observations of Eight Sources Discovered by INTEGRAL
• Swift J2218.4+1925: a new hard X-ray selected Polar observed with XMM-Newton
• RX J1039.7-0507: A New Intermediate Polar and Probable Recent Nova, possessing a large Reflection Effect
• Discovery of a new pulsating X-ray source with a 1549.1-s period, AX J183220-0840
• IGR J14257-6117, a magnetic accreting white dwarf with a very strong X-ray orbital modulation
• Chandra, NuSTAR, and Optical Observations of the Cataclysmic Variables IGR J17528-2022 and IGR J20063+3641
• Time-Resolved Photometry of the Optical Counterpart of Swift J2319.4+2619
• Investigating the true nature of three hard X-ray sources

Cited by in corpus (7)

• Classifying Unidentified X-ray Sources in the Chandra Source Catalog Using a Multiwavelength Machine-learning Approach
• Compact white-dwarf binaries in the combined SRG/eROSITA/SDSS eFEDS survey
• Periodicity from X-ray sources within the inner Galactic disk
• Classifying IGR J15038-6021 as a magnetic CV with a massive white dwarf
• X-ray spectroscopy method of white dwarf mass determination in intermediate polars. External systematic uncertainties
• XMM-Newton and NuSTAR discovery of a likely IP candidate XMMU J173029.8-330920 in the Galactic Disk
• Galactic X-ray Transients in the First eROSITA All Sky Survey