Shadows of Einstein–dilaton–Gauss–Bonnet black holes
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 und...
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2017-05-01
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doaj-bf793ce7b4be4af8b67370ce9922bf4f2020-11-24T23:14:48ZengElsevierPhysics Letters B0370-26931873-24452017-05-01768C37337910.1016/j.physletb.2017.03.020Shadows of Einstein–dilaton–Gauss–Bonnet black holesPedro V.P. Cunha0Carlos A.R. Herdeiro1Burkhard Kleihaus2Jutta Kunz3Eugen Radu4Departamento de Física da Universidade de Aveiro and Centre for Research and Development in Mathematics and Applications (CIDMA), Campus de Santiago, 3810-183 Aveiro, PortugalDepartamento de Física da Universidade de Aveiro and Centre for Research and Development in Mathematics and Applications (CIDMA), Campus de Santiago, 3810-183 Aveiro, PortugalInstitute of Physics, University of Oldenburg, Oldenburg, 26111, GermanyInstitute of Physics, University of Oldenburg, Oldenburg, 26111, GermanyDepartamento de Física da Universidade de Aveiro and Centre for Research and Development in Mathematics and Applications (CIDMA), Campus de Santiago, 3810-183 Aveiro, PortugalWe 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.http://www.sciencedirect.com/science/article/pii/S0370269317302071 |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Pedro V.P. Cunha Carlos A.R. Herdeiro Burkhard Kleihaus Jutta Kunz Eugen Radu |
spellingShingle |
Pedro V.P. Cunha Carlos A.R. Herdeiro Burkhard Kleihaus Jutta Kunz Eugen Radu Shadows of Einstein–dilaton–Gauss–Bonnet black holes Physics Letters B |
author_facet |
Pedro V.P. Cunha Carlos A.R. Herdeiro Burkhard Kleihaus Jutta Kunz Eugen Radu |
author_sort |
Pedro V.P. Cunha |
title |
Shadows of Einstein–dilaton–Gauss–Bonnet black holes |
title_short |
Shadows of Einstein–dilaton–Gauss–Bonnet black holes |
title_full |
Shadows of Einstein–dilaton–Gauss–Bonnet black holes |
title_fullStr |
Shadows of Einstein–dilaton–Gauss–Bonnet black holes |
title_full_unstemmed |
Shadows of Einstein–dilaton–Gauss–Bonnet black holes |
title_sort |
shadows of einstein–dilaton–gauss–bonnet black holes |
publisher |
Elsevier |
series |
Physics Letters B |
issn |
0370-2693 1873-2445 |
publishDate |
2017-05-01 |
description |
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. |
url |
http://www.sciencedirect.com/science/article/pii/S0370269317302071 |
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