Accretion in dipole magnetic fields: flow structure and X-ray emission of accreting white dwarfs

Abstract

Field-channelled accretion flows occur in a variety of astrophysical objects, including T Tauri stars,magnetic cataclysmic variables and X-ray pulsars. We consider a curvilinear coordinate system and derive a general hydrodynamic formulation for accretion onto stellar objects confined by a stellar dipole magnetic field. The hydrodynamic equations are solved to determine the velocity, density and temperature profiles of the flow. We use accreting magnetic white-dwarf stars as an illustrative example of astrophysical applications. Our calculations show that the compressional heating due to the field geometry is as important as radiative cooling and gravity in determining the structure of the post-shock flow in accreting white-dwarf stars. The generalisation of the formulation to accretion flows channelled by higher-order fields and the applications to other astrophysical systems are discussed.

Accepted A&A

References in corpus (10)

• Spin-Up/Spin-Down of Magnetized Stars with Accretion Disks and Outflows
• Three-dimensional Simulations of Disk Accretion to an Inclined Dipole: I. Magnetospheric Flow at Different Theta
• The Structure and Emission of the Accretion Shock in T Tauri Stars II: the Ultraviolet Continuum Emission
• X-ray emission from a metal depleted accretion shock onto the classical T Tauri star TW Hya
• Effects of Gravity on the Structure of Postshock Accretion Flows in Magnetic Cataclysmic Variables
• Funnel Flows from Disks to Magnetized Stars
• An XMM-Newton timing analysis of the eclipsing polar DP Leo
• Perturbative Analysis of Two-Temperature Radiative Shocks with Multiple Cooling Processes
• Stability analyses of two-temperature radiative shocks: formulation, eigenfunctions, luminosity response and boundary conditions
• The lower boundary of the accretion column in magnetic cataclysmic variables

Cited by in corpus (23)

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• Hard X-ray Cataclysmic Variables
• Magnetically Controlled Accretion Flows onto Young Stellar Objects
• GK Per and EX Hya: Intermediate polars with small magnetospheres
• A New Two-Fluid Radiation-Hydrodynamical Model for X-ray Pulsar Accretion Columns
• INTEGRAL view on Cataclysmic Variables and Symbiotic Binaries
• Super-Eddington Emission from Accreting, Highly Magnetised Neutron Stars with a Multipolar Magnetic Field
• X-ray emissions from two-temperature accretion flows within a dipole magnetic funnel
• X-ray reflection from cold white dwarfs in magnetic cataclysmic variables
• 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
• Photoionized features in the X-ray spectrum of EX Hydrae
• Influence of Compton scattering on the broad-band X-ray spectra of intermediate polars
• Application of a new X-ray reflection model to V1223 Sagittarii
• Stokes imaging of AM Her systems using 3D inhomogeneous models - I. Description of the code and an application to V834 Cen
• Breaking the degeneracy in magnetic cataclysmic variable X-ray spectral modeling using X-ray light curves
• Features of the Accretion in the EX Hydrae System: Results of Numerical Simulation
• Accretion column structure of magnetic cataclysmic variables from X-ray spectroscopy
• Optical observations and cyclops post-shock region modelling of the polar V348 Pav
• X-ray spectroscopy method of white dwarf mass determination in intermediate polars. External systematic uncertainties