Effect of thermal conduction on accretion shocks in relativistic magnetized flows around rotating black holes

TL;DR

This study investigates how thermal conduction influences shock formation and emission spectra in relativistic, magnetized accretion flows around rotating black holes, revealing parameter-dependent shock properties and spectral luminosity changes.

Contribution

It provides a self-consistent analysis of shock dynamics and spectral features in magnetized accretion flows considering thermal conduction and cooling processes, extending previous models.

Findings

Shock properties depend on conduction, magnetic, and viscosity parameters.

Critical conduction threshold determines shock formation viability.

Enhanced conduction and magnetic fields increase spectral luminosity.

Abstract

We examine the effects of thermal conduction on relativistic, magnetized, viscous, advective accretion flows around rotating black holes considering bremsstrahlung and synchrotron cooling processes. Assuming the toroidal component of magnetic fields as the dominant one, we self-consistently solve the steady-state fluid equations to derive the global transonic accretion solutions for a black hole of spin $a_{\rm k}$. Depending on the model parameters, the magnetized accretion flow undergoes shock transitions and shock-induced global accretion solutions persist over a wide range of model parameters including the conduction parameter ($\Upsilon_{\rm s}$), plasma-$\beta$, and viscosity parameter ($\alpha_{\rm B}$). We find that the shock properties -- such as shock radius ($r_{\rm s}$), compression ratio ($R$), and shock strength ($S$) -- are regulated by $\Upsilon_{\rm s}$, plasma $\beta$, and $\alpha_{\rm B}$. Furthermore, we compute the critical conduction parameter ($\Upsilon_{\rm s}^{\rm cri}$), a threshold beyond which shock formation ceases to exist, and investigate its dependence on plasma-$\beta$ and $\alpha_{\rm B}$ for both weakly rotating ($a_{\rm k} \rightarrow 0$) and rapidly rotating ($a_{\rm k} \rightarrow 1$) black holes. Finally, we examine the spectral energy distribution (SED) of the accretion disc and observe that increased thermal conduction and magnetic field strength lead to more luminous emission spectra from black hole sources.