Gravitational deflection of light and shadow cast by rotating Kalb-Ramond black holes

By Sushant G. Ghosh, Anzhong Wang. Physical Review D, 2020

153 citations recorded by the source corpus.

The nonminimal coupling of the nonzero vacuum expectation value of the self-interacting antisymmetric Kalb-Ramond field with gravity leads to a power-law hairy black hole having a parameter s, which encompasses the Reissner-Nordstrom black hole (s=1). We obtain the axially symmetric counterpart of this hairy solution, namely, the rotating Kalb-Ramond black hole, which encompasses, as special cases, Kerr (s=0) and Kerr-Newman (s=1) black holes. Interestingly, for a set of parameters (M, a, and Γ), there exists an extremal value of the Kalb-Ramond parameter (s=se), which corresponds to an extremal black hole with degenerate horizons, while for s se. We find that the extremal value se is also influenced by these parameters. The black hole shadow size decreases monotonically and the shape gets more distorted with an increasing s; in turn, shadows of rotating Kalb-Ramond black holes are smaller and more distorted than the corresponding Kerr black hole shadows. We investigate the effect of the Kalb-Ramond field on the rotating black hole spacetime geometry and analytically deduced corrections to the light deflection angle from the Kerr and Schwarzschild black hole values. The deflection angle for Sgr A* and the shadow caused by the supermassive black hole M87* are included and compared with analogous results of Kerr black holes. The inferred circularity deviation ΔC≤0.10 for the M87* black hole merely constrains the Kalb-Ramond field parameter, whereas shadow angular diameter θd=42±3  μas, within the 1σ region, places bounds Γ≤0.09205 for s=1 and Γ≤0.02178 for s=3.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/80e138949dd71bcec14f13c58af675717dc60256

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In Astronomy and Astrophysics

1. D. Mota
2. A. Allahyari
3. Mohsen Khodadi
4. S. Vagnozzi
5. M. Jamil
6. Chengzhou Liu
7. M. Azreg-Aïnou
8. Anzhong Wang

Citations in the corpus

• Shadow and quasinormal modes of a rotating loop quantum black hole (2020, background): “[46, 49, 108–110] for examples.”
• Black holes with scalar hair in light of the Event Horizon Telescope (2020, background): “For an incomplete list of works in this direction, see for instance [115–167].”