Observational features of reflection asymmetric black holes
Abstract
The Kerr spacetime is symmetric with respect to a welldefined equatorial plane. When testing the equatorial reflection symmetry of an isolated black hole, one is at the same time testing the Kerr hypothesis in General Relativity. In this work, we investigate the possible observational features when a Keplerian disk is surrounding a rotating black hole without reflection symmetry. When such symmetry is broken, generically, the photon trajectories around the black hole and the Keplerian orbits on the accretion disk are distorted vertically away from the equatorial plane by an amount that depends on their distance to the black hole. In the reflection asymmetric spacetime we are considering, these two kinds of orbits are distorted in opposite directions. Interestingly, while the size and shape of black hole shadows closely resemble those of Kerr black holes, distinct observational characteristics can emerge in the disk image and emission line profiles. When observing the disk edgeon, a pronounced concave shape may appear along its innermost edge on the incoming side. Furthermore, distinctive hornlike features might be observed on the spectral line profile at the blueshifted side. These special features can serve as compelling indicators of the reflection asymmetry present in rotating black holes.
 Publication:

Journal of Cosmology and Astroparticle Physics
 Pub Date:
 September 2024
 DOI:
 10.1088/14757516/2024/09/043
 arXiv:
 arXiv:2404.07055
 Bibcode:
 2024JCAP...09..043C
 Keywords:

 gravity;
 modified gravity;
 astrophysical fluid dynamics;
 General Relativity and Quantum Cosmology;
 Astrophysics  High Energy Astrophysical Phenomena;
 High Energy Physics  Theory
 EPrint:
 22 pages, 8 figures. Matching published version