The Image of Scalar Hairy Black Holes with Asymmetric Potential

TL;DR

This paper analyzes the optical appearance and observational signatures of scalar hairy black holes with asymmetric potential, exploring their accretion disk images, photon spheres, and shadows to compare with astronomical observations.

Contribution

It provides a detailed numerical study of the optical features of scalar hairy black holes with asymmetric potential, including shadow size and spectral shifts, linking theoretical models with observational data.

Findings

Photon sphere and ISCO radii vary with scalar hair parameters.

Predicted black hole shadows are consistent with EHT observations.

Spectral shifts reveal gravitational and Doppler effects in accretion disks.

Abstract

Black hole accretion disks are a fascinating topic in astrophysics, as they play a crucial role in several high-energy situations. This paper investigates the optical appearance of scalar hairy black holes (SHBHs) with asymmetric potential, a numerical solution obtained in Phys. Rev. D 73, 084002 (2006) and discussed in Phys.Rev.D 108 (2023) 4, 044020. Since the solution is spherically symmetric and surrounded by a thin accretion disk, we base our analysis on the work of J.~P. Lumininet (1979). We discuss the behavior of the effective potential for massive and massless particles, the innermost stable circular orbits (ISCO), and the photon sphere radius for different SHBHs. The study includes the plots of isoradial curves and spectral shifts arising from gravitational and Doppler shifts by considering direct and secondary images. Based on the work of Page and Thorne (1974), we also investigate the intrinsic intensity of radiation emitted by the disk at a given radius, which allows the calculation of the distribution of observed bolometric flux. We use the angular size of the shadow reported by the EHT for Sagittarius A* and M87* to constrain the SHBHs parameters.