Two-temperature accretion flows around strongly magnetized stars and their spectral analysis

Abstract

We investigate two-temperature accretion flows onto strongly magnetized compact stars. Matter is accreted in the form of an accretion disc upto the disc radius ($r_{\mathrm{d}}$), where, the magnetic pressure exceeds both the gas and ram pressure and thereafter the matter is channelled along the field lines onto the poles. We solve the equations of motion self-consistently along the field lines, incorporating radiative processes like bremsstrahlung, synchrotron and inverse-Comptonization. For a given set of constants of motion, the equations of motion do not produce unique transonic solution. Following the second law of thermodynamics the solution with the highest entropy is selected and thereby eliminating the degeneracy in solution. We study the properties of these solutions and obtain corresponding spectra as a function of the magnetic field ($B_{\ast }$), spin period ($P$) and accretion rate of the star ($\dot{M}$). A primary shock is always formed just near the surface. The enhanced radiative processes in this post-shock region slows down the matter and it finally settles on the surface of the star. This post-shock region contributes to $\gtrsim 99.99\%$ of the total luminosity obtained from the accretion flow. It is still important to study the full accretion flow because secondary shocks may be present for some combination of $B_{\ast }$, $P$ and $\dot{M}$ in addition to primary shocks. We find that secondary shocks, if present, produce an extended emission at higher energies in the spectra.

arXiv comment18 pages, 17 figures and accepted for publication in MNRAS

References in corpus (37)

• Advection-Dominated Accretion: Underfed Black Holes and Neutron Stars
• Hot Accretion Flows Around Black Holes
• Nonthermal Electrons in Radiatively Inefficient Accretion Flow Models of Sagittarius A*
• Thermal and Bulk Comptonization in Accretion-Powered X-Ray Pulsars
• Spectral Formation in Accreting X-Ray Pulsars: Bimodal Variation of the Cyclotron Energy with Luminosity
• Spectrum of Optically Thin Advection Dominated Accretion Flow around a Black Hole: Application to Sgr A*
• Magneto-centrifugally driven winds: comparison of MHD simulations with theory
• Two-temperature, Magnetically Arrested Disc simulations of the jet from the supermassive black hole in M87
• Radiative, two-temperature simulations of low luminosity black hole accretion flows in general relativity
• Pulsing ULXs: tip of the iceberg?
• Thermal synchrotron radiation and its Comptonization in compact X-ray sources
• Equation of State in Numerical Relativistic Hydrodynamics
• Effects of Fluid Composition on Spherical Flows around Black Holes
• An ultraluminous nascent millisecond pulsar
• No magnetars in ULXs
• Heating and Cooling of Hot Accretion Flows by Non Local Radiation
• Pulsing and Non-Pulsing ULXs: the Iceberg Emerges
• Self-Similar Hot Accretion Flow onto a Neutron Star
• Spectral Formation in X-Ray Pulsars: Bulk Comptonization in the Accretion Shock
• Funnel Flows from Disks to Magnetized Stars
• Particle Acceleration and the Formation of Relativistic Outflows in Viscous Accretion Disks with Shocks
• Properties of Two-Temperature Dissipative Accretion Flow Around Black Holes
• Spectral Formation in X-Ray Pulsar Accretion Columns
• A New Two-Fluid Radiation-Hydrodynamical Model for X-ray Pulsar Accretion Columns
• Inner Boundary Conditions for Advection-Dominated Accretion onto Black Holes
• Dynamical and Radiative Properties of X-ray Pulsar Accretion Columns: Phase-Averaged Spectra
• Properties of two-temperature magnetized advective accretion flow around rotating black hole
• Two-temperature accretion flows in magnetic cataclysmic variables: Structures of post-shock emission regions and X-ray spectroscopy
• Two temperature solutions and emergent spectra from relativistic accretion discs around black holes
• Magnetic angle evolution in accreting neutron stars
• Beamed emission from a neutron-star ULX in a GRRMHD simulation
• General relativistic two-temperature accretion solutions for spherical flows around black holes
• Magnetic Inclination Evolution of Accreting Neutron Stars in Intermediate/Low-Mass X-ray Binaries
• Funnel-flow accretion onto highly magnetized neutron stars and shock generation
• Study of magnetized accretion flow with variable $\Gamma$ equation of state
• Two-temperature radiative hot accretion flow around neutron stars
• Study of Magnetized accretion flow with cooling processes

Cited by in corpus (1)

• Iterative Relaxation Method to Obtain Global Transonic Flows around Compact Objects