Dynamics of thin accretion disks and accretion around a charged-PFDM black hole

Abstract

This paper investigates the dynamical behavior of steady spherical accretion onto a static, magnetically charged black hole embedded in a perfect fluid dark matter (PFDM) background. Using the shadow observations of M87* from the Event Horizon Telescope (EHT), we establish constraints on the parameter space for the magnetic charge and the PFDM parameter. Within this constrained range, we analyze the orbital dynamics of particles in a thin accretion disk surrounding the black hole and find that the black hole parameters significantly influence the effective potential, angular velocity, specific energy, and specific angular momentum of the particles. Subsequently, we calculate the radiative energy flux, temperature profile, and observed spectrum of the disk. Our results show that, while the local radiative flux and temperature at a given radius are lower for the charged-PFDM black hole compared to a Schwarzschild black hole, its overall radiative efficiency and total luminosity are higher. Finally, we explore the spherically symmetric, steady-state accretion process around the black hole, revealing how the parameters govern how the fluid velocity, density profile, and black hole mass accretion rate are influenced.

Figures (11)

• Figure 1: The phase diagram for the parameter space $(a/M,\zeta/M)$ of charged-PFDM black hole
• Figure 2: EHT-constrained parameter space of M87* candidate charged black holes in PFDM background. The horizontal axis is PFDM parameter $\zeta/M$, left vertical axis is magnetic charge parameter $a/M$, and the right color bar links to $R_s/M$. The black dashed line marks extreme black holes (black holes exist below it); the area between two curves is constrained by EHT observations of M87*.
• Figure 3: The effective potential $V_{eff}$ depends on the radial coordinate $r$, and its variation characteristics under different parameter combinations are as follows (a) for $\zeta=-0.15$, $a=0.5$, with different values of $L$ (b) for $L=5$, $\zeta=-0.15$ with different values of $a$ (c) for $L=5$, $a=0.5$ with different values of $\zeta$.
• Figure 4: Angular velocity $\Omega$ versus $r$ (a) for $a=0.5$, varying $\zeta$, (b) for $\zeta=-0.15$, varying $a$.
• Figure 5: The distributions of specific energy and specific angular momentum are shown as functions of the radial coordinate $r$. The left panel displays results for different PFDM parameter $\zeta$ values with $a = 0.5$ , while the right panel corresponds to different magnetic charge parameter a values with $\zeta=-0.15$.