Breaking the degeneracy in magnetic cataclysmic variable X-ray spectral modeling using X-ray light curves

Abstract

We present an analysis of mock X-ray spectra and light curves of magnetic cataclysmic variables using an upgraded version of the 3D CYCLOPS code. This 3D representation of the accretion flow allows us to properly model total and partial occultation of the post-shock region by the white dwarf as well as the modulation of the X-ray light curves due to the phase-dependent extinction of the pre-shock region. We carried out detailed post-shock region modeling in a four-dimensional parameter space by varying the white dwarf mass and magnetic field strength as well as the magnetosphere radius and the specific accretion rate. To calculate the post-shock region temperature and density profiles, we assumed equipartition between ions and electrons, took into account the white dwarf gravitational potential, the finite size of the magnetosphere and a dipole-like magnetic field geometry, and considered cooling by both bremsstrahlung and cyclotron radiative processes. By investigating the impact of the parameters on the resulting X-ray continuum spectra, we show that there is an inevitable degeneracy in the four-dimensional parameter space investigated here, which compromises X-ray continuum spectral fitting strategies and can lead to incorrect parameter estimates. However, the inclusion of X-ray light curves in different energy ranges can break this degeneracy, and it therefore remains, in principle, possible to use X-ray data to derive fundamental parameters of magnetic cataclysmic variables, which represents an essential step toward understanding their formation and evolution.

arXiv comment42 pages, accepted for publication in The Astrophysical Journal Supplement Series

References in corpus (40)

• Magnetic White Dwarfs
• X-ray Emissions from Accreting White Dwarfs: a Review
• A new radiative cooling curve based on an up to date plasma emission code
• Magnetic fields in isolated and interacting white dwarfs
• The origin and evolution of magnetic white dwarfs in close binary stars
• Effects of Gravity on the Structure of Postshock Accretion Flows in Magnetic Cataclysmic Variables
• The gas-to-extinction ratio and the gas distribution in the Galaxy
• RXTE broadband X-ray spectra of intermediate polars and white dwarf mass estimates
• White dwarf masses in intermediate polars observed with the Suzaku satellite
• Hard X-ray view on intermediate polars in the Gaia era
• Quenching of the accretion disk strong aperiodic variability at the magnetospheric boundary
• The energy balance in polars revisited
• The Accretion Flows and Evolution of Magnetic Cataclysmic Variables
• Determining the mass of the accreting white dwarf in magnetic CVs using data
• Accretion physics of AM Herculis binaries, I. Results from one-dimensional stationary radiation hydrodynamics
• Unambiguous Detection of Reflection in Magnetic Cataclysmic Variables: Joint NuSTAR-XMM-Newton Observations of Three Intermediate Polars
• Measuring the masses of magnetic white dwarfs: A NuSTAR Legacy Survey
• GK Per and EX Hya: Intermediate polars with small magnetospheres
• Broad-band characteristics of seven new hard X-ray selected cataclysmic variables
• Aperiodic optical variability of intermediate polars - cataclysmic variables with truncated accretion disks
• Accretion in dipole magnetic fields: flow structure and X-ray emission of accreting white dwarfs
• Observational evidence for matter propagation in accretion flows
• Identifying IGR J14091-6108 as a magnetic CV with a massive white dwarf using X-ray and optical observations
• Suzaku Observation of the Intermediate Polar V1223 Sagittarii
• X-ray emissions from two-temperature accretion flows within a dipole magnetic funnel
• X-ray reflection from cold white dwarfs in magnetic cataclysmic variables
• Magnetic dynamos in white dwarfs -- I. Explaining the dearth of bright intermediate polars in globular clusters
• Numerical simulations of high-energy flows in accreting magnetic white dwarfs
• Spectroscopic Observations of the Intermediate Polar EX Hydrae in Quiescence
• Testing the cooling flow model in the intermediate polar EX Hydrae
• On the area of accretion curtains from fast aperiodic time variability of the intermediate polar EX Hya
• Constraining the accretion geometry of the intermediate polar EX Hya using NuSTAR, Swift and Chandra observations
• Photoionized features in the X-ray spectrum of EX Hydrae
• Influence of Compton scattering on the broad-band X-ray spectra of intermediate polars
• Stokes imaging of AM Her systems using 3D inhomogeneous models-II. Modelling X-ray and optical data of CP Tucanae
• Multiwavelength study of RX J2015.6+3711: a magnetic cataclysmic variable with a 2-hr spin period
• Stokes imaging of AM Her systems using 3D inhomogeneous models - I. Description of the code and an application to V834 Cen
• Accretion column structure of magnetic cataclysmic variables from X-ray spectroscopy
• Optical observations and cyclops post-shock region modelling of the polar V348 Pav
• The effect of two-temperature post-shock accretion flow on the linear polarization pulse in magnetic cataclysmic variables

Cited by in corpus (4)

• Formation and Evolution of Accreting Compact Objects
• Cyclotron emitting magnetic white dwarfs in post common envelope binaries discovered with the Zwicky Transient Facility
• Dynamical mass of the white dwarf in XY Ari: a test for intermediate polar X-ray spectral models
• Gravitational Redshift Detection from the Magnetic White Dwarf Harbored in RX J1712.6-2414