Black Hole Parameter Estimation from Its Shadow
By Rahul Kumar, Sushant G. Ghosh. Astrophysical Journal, 2018
218 citations recorded by the source corpus.
The Event Horizon Telescope (EHT), a global submillimeter wavelength very long baseline interferometry array, unveiled event-horizon–scale images of the supermassive black hole M87* as an asymmetric bright emission ring with a diameter of 42 ± 3 μas, and it is consistent with the shadow of a Kerr black hole of general relativity. A Kerr black hole is also a solution of some alternative theories of gravity, while several modified theories of gravity admit non-Kerr black holes. While earlier estimates for the M87* black hole mass, depending on the method used, fall in the range , the EHT data indicated a mass for the M87* black hole of (6.5 ± 0.7) × 109 M⊙. This offers another promising tool to estimate black hole parameters and to probe theories of gravity in its most extreme region near the event horizon. The important question arises: Is it possible by a simple technique to estimate black hole parameters from its shadow, for arbitrary models? In this paper, we present observables, expressed in terms of ordinary integrals, characterizing a haphazard shadow shape to estimate the parameters associated with black holes, and then illustrate its relevance to four different models: Kerr, Kerr–Newman, and two rotating regular models. Our method is robust, accurate, and consistent with the results obtained from existing formalism, and it is applicable to more general shadow shapes that may not be circular due to noisy data.
Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics
View Paper: https://www.semanticscholar.org/paper/567386a901f512be1881060124095a34dd685146
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Citations in the corpus
- Rotating black holes in 4D Einstein-Gauss-Bonnet gravity and its shadow (2020, background): “The size and the amount of deviation from the circularity are measurable quantities and therefore, we introduce the shadow observables, namely, shadow area A and oblateness D, for the characterization of shadows [96, 105]”
- Silhouette of M87*: A new window to peek into the world of hidden dimensions (2019, methodology): “Having discussed the basic properties of the braneworld BH shadow, we now describe the observables which can be used to test the hairs of the BH [63].”
- Calculating black hole shadows: Review of analytical studies (2021, unknown): “Nazarova, Silhouettes of invisible black holes, Physics-Uspekhi 63 (2020) 583 [106] R.”