Two temperature solutions and emergent spectra from relativistic accretion discs around black holes

TL;DR

This paper investigates the degeneracy of solutions in two-temperature accretion disks around black holes, demonstrating how entropy measures can resolve ambiguities and how system parameters influence spectra and luminosity.

Contribution

It introduces an entropy-based method to remove solution degeneracy in accretion disk models, improving understanding of spectral dependencies on black hole parameters.

Findings

Spectra depend on constants of motion, ranging from radiatively inefficient to luminous flows.

Increasing black hole mass enhances luminosity and spectral bandwidth.

Accretion rate has limited impact on spectral frequency range.

Abstract

An accreting system in two-temperature regime, admits multiple solutions for the same set of constants of motion, producing widely different spectra. Comparing observed spectrum with that derived from a randomly chosen accretion solution, will give us a wrong estimation of the accretion parameters of the system. The form of entropy measure obtained by us, have helped in removing the degeneracy of the solutions, allowing us to understand the physics of the system, shorn of arbitrary assumptions. In this work, we have shown how the spectra and luminosities of an accreting system depends on the constants of motion, producing solutions ranging from radiatively inefficient flows to luminous flows. Increase in BH mass quantitatively changes the system, makes the system more luminous and the spectral bandwidth also increases. Higher BH mass system spans from radio to gamma-rays. However, increasing the accretion rate around a BH of certain mass, has little influence in the frequency range of the spectra.