Time dependence of advection dominated accretion flow around a rotating compact object

TL;DR

This paper investigates the time-dependent behavior of advection-dominated accretion flows around rotating compact objects, revealing how rotation influences flow structure and energy characteristics.

Contribution

It introduces a time-dependent model of ADAF including rotation effects and uses self-similar solutions to explore dynamical behaviors not seen in steady flows.

Findings

Physical quantities depend on the rotation parameter.

Flow behavior differs for co-rotating and counter-rotating cases.

Bernoulli function becomes more positive with increased rotation effects.

Abstract

Time evolution of advection-dominated accretion flow (ADAF) around a rotating compact object is presented. The equations of time-dependent of fluid including the Coriolis force along with the centrifugal and pressure gradient forces are derived. In this research, it is assumed that angular momentum transport is due to viscous turbulence and the {\alpha}-prescription is used for the kinematic coefficient of viscosity. Moreover, the general relativistic effects are neglected. In order to solve the equations, we have used a self-similar solution. The solutions show that the behaviour of the physical quantities in a dynamical ADAF is different from that for a steady accretion flow. Our results indicate that the physical quantities are dependent of rotation parameter which is defined as the ratio of the intrinsic angular velocity of the central body to the angular velocity of disc. Also, the effect of rotation parameter on these quantities is different for co and counter-rotating flows. The solution shows that by increasing the rotation parameter a, inflow-outflow region approaches the central object for co-rotating flow and moves outward for counter-rotating flow. We find that when flow is fully advection dominated (f ! 1), the entire gas has positive Bernoulli function. Also, we suggest that the Bernoulli function becomes more positive when the effect of rotation on the structure of disc decreases.