Study of general relativistic magnetohydrodynamic accretion flow around black holes

Abstract

We present a novel approach to study the global structure of steady, axisymmetric, advective, geometrically thin, magnetohydrodynamic (MHD) accretion flow around black holes in full general relativity (GR). Considering ideal MHD conditions and relativistic equation of state (REoS), we solve the governing equations to obtain all possible smooth global accretion solutions. We examine the dynamical and thermodynamical properties of accreting matter in terms of the flow parameters, namely energy ($\mathcal{E}$), angular momentum ($\mathcal{L}$), and local magnetic fields. For a thin GRMHD flow, we observe that toroidal component ($b^{\varphi }$) of the magnetic fields generally dominates over radial component ($b^r$) at the disk equatorial plane. This evidently suggests that toroidal magnetic field indeed plays important role in regulating the disk dynamics. We further notice that the disk remains mostly gas pressure ($p_{\mathrm{gas}}$) dominated ($\beta =p_{\mathrm{gas}}/p_{\mathrm{mag}}>1$, $p_{\mathrm{mag}}$ refers magnetic pressure) except at the near horizon region, where magnetic fields become dynamically important ($\beta \sim 1$). We observe that Maxwell stress is developed that eventually yields angular momentum transport inside the disk. Towards this, we calculate the viscosity parameter ($\alpha$) that appears to be radially varying. In addition, we examine the underlying scaling relation between $\alpha$ and $\beta$, which clearly distinguishes two domains coexisted along the radial extent of the disk. Finally, we discuss the utility of the present formalism in the realm of GRMHD simulation studies.

16 pages, 11 figures, Accepted in MNRAS

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• General relativistic hydrodynamic simulations of perturbed transonic accretion
• Global Transonic Solution of Hot Accretion Flow with Thermal Conduction
• Accretion flow in deformed Kerr spacetime: Spectral energy distributions from free-free emission
• General relativistic viscous accretion flow around Konoplya-Zhidenko black hole
• Hamiltonian Formulation of Relativistic Magnetohydrodynamic Accretion on a General Spherically Symmetric and Static Black Hole: Quantum effects on Shock States