Shadows of Einstein–dilaton–Gauss–Bonnet black holes

By P. Cunha, Carlos A. R. Herdeiro, B. Kleihaus, Jutta Kunz, Eugen Radu. 2016

196 citations recorded by the source corpus.

Abstract We study the shadows of the fully non-linear, asymptotically flat Einstein–dilaton–Gauss–Bonnet (EdGB) black holes (BHs), for both static and rotating solutions. We find that, in all cases, these shadows are smaller than for comparable Kerr BHs, i.e. with the same total mass and angular momentum under similar observation conditions. In order to compare both cases we provide quantitative shadow parameters, observing in particular that the differences in the shadows mean radii are never larger than the percent level. Therefore, generically, EdGB BHs cannot be excluded by (near future) shadow observations alone. On the theoretical side, we find no clear signature of some exotic features of EdGB BHs on the corresponding shadows, such as the regions of negative (Komar, say) energy density outside the horizon. We speculate that this is due to the fact that the Komar energy interior to the light rings (or more precisely, the surfaces of constant radial coordinate that intersect the light rings in the equatorial plane) is always smaller than the ADM mass, and consequently the corresponding shadows are smaller than those of comparable Kerr BHs. The analysis herein provides a clear example that it is the light ring impact parameter, rather than its “size”, that determines a BH shadow.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/d877631160b11ec100d7f055e29bd879a335793b

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In Astronomy and Astrophysics

1. P. Cunha
2. Carlos A. R. Herdeiro
3. M. Jamil
4. Qiang Wu
5. Tao Zhu
6. K. Jusufi
7. Eugen Radu
8. V. Cardoso

In Nuclear and High Energy Physics

1. P. Cunha
2. Carlos A. R. Herdeiro
3. M. Jamil
4. Qiang Wu
5. Tao Zhu
6. K. Jusufi
7. V. Cardoso
8. Eugen Radu

Citations in the corpus

• Shadows and strong gravitational lensing: a brief review (2018, background): “These BH solutions can moreover be perturbatively stable, asymptotically flat and regular, possessing a dilatonic field as a form of nonindependent hair [66, 83].”
• Shadows and deflection angle of charged and slowly rotating black holes in Einstein-Æther theory (2019, background): “Some notable results of black hole shadows are already discussed in the literature, to list a few: Schwarzschild black hole surrounded by a Bach-Weyl ring [6]; Einstein-dilaton-GaussBonnet black hole [7]; Konoplya-Zhidenko black hole [8]; Einstein-Maxwell-Chern-Simon black hole [9]; EinsteinMaxwell-”
• The shape of the black hole photon ring: A precise test of strong-field general relativity (2020, unknown): “[41,42]) or from a parametrized deviation away from the Kerr metric (e.g., Refs.”