Shadows in conformally related gravity theories
Null geodesics are invariant under a conformal transformation, and thus it might seem natural to assume that the observables corresponding to the shadow of a space-time are also conformally invariant. Here, we argue instead, that since the Arnowitt-Deser-Misner mass and the active gravitational mass...
| Main Authors: | , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Elsevier
2022-06-01
|
| Series: | Physics Letters B |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S037026932200243X |
| _version_ | 1828345296852090880 |
|---|---|
| author | Kunal Pal Kuntal Pal Rajibul Shaikh Tapobrata Sarkar |
| author_facet | Kunal Pal Kuntal Pal Rajibul Shaikh Tapobrata Sarkar |
| author_sort | Kunal Pal |
| collection | DOAJ |
| description | Null geodesics are invariant under a conformal transformation, and thus it might seem natural to assume that the observables corresponding to the shadow of a space-time are also conformally invariant. Here, we argue instead, that since the Arnowitt-Deser-Misner mass and the active gravitational mass of an asymptotically flat space-time are not, in general, invariant under such conformal transformations, the shadow radius for photon motion in a space-time would be quantitatively different, when viewed from two different conformally related frames, although the expression for the shadow radius is similar. We then use this fact to propose a novel method to constrain the relevant parameters in a gravity theory conformally related to general relativity. As examples of our method, we constrain the parameter space in Brans-Dicke theory, and a class of brane-world gravity models, by using the recent observational data of M87⁎ by the Event Horizon Telescope. |
| first_indexed | 2024-04-14T00:08:47Z |
| format | Article |
| id | doaj.art-7741f9616c6743d5a5220a9dc4470995 |
| institution | Directory Open Access Journal |
| issn | 0370-2693 |
| language | English |
| last_indexed | 2024-04-14T00:08:47Z |
| publishDate | 2022-06-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Physics Letters B |
| spelling | doaj.art-7741f9616c6743d5a5220a9dc44709952022-12-22T02:23:25ZengElsevierPhysics Letters B0370-26932022-06-01829137109Shadows in conformally related gravity theoriesKunal Pal0Kuntal Pal1Rajibul Shaikh2Tapobrata Sarkar3Department of Physics, Indian Institute of Technology Kanpur, Kanpur 208016, IndiaDepartment of Physics, Indian Institute of Technology Kanpur, Kanpur 208016, IndiaDepartment of Physics, Indian Institute of Technology Kanpur, Kanpur 208016, India; Institute of Convergence Fundamental Studies & School of Liberal Arts, Seoul National University of Science and Technology, Seoul 01811, Republic of KoreaDepartment of Physics, Indian Institute of Technology Kanpur, Kanpur 208016, India; Corresponding author.Null geodesics are invariant under a conformal transformation, and thus it might seem natural to assume that the observables corresponding to the shadow of a space-time are also conformally invariant. Here, we argue instead, that since the Arnowitt-Deser-Misner mass and the active gravitational mass of an asymptotically flat space-time are not, in general, invariant under such conformal transformations, the shadow radius for photon motion in a space-time would be quantitatively different, when viewed from two different conformally related frames, although the expression for the shadow radius is similar. We then use this fact to propose a novel method to constrain the relevant parameters in a gravity theory conformally related to general relativity. As examples of our method, we constrain the parameter space in Brans-Dicke theory, and a class of brane-world gravity models, by using the recent observational data of M87⁎ by the Event Horizon Telescope.http://www.sciencedirect.com/science/article/pii/S037026932200243X |
| spellingShingle | Kunal Pal Kuntal Pal Rajibul Shaikh Tapobrata Sarkar Shadows in conformally related gravity theories Physics Letters B |
| title | Shadows in conformally related gravity theories |
| title_full | Shadows in conformally related gravity theories |
| title_fullStr | Shadows in conformally related gravity theories |
| title_full_unstemmed | Shadows in conformally related gravity theories |
| title_short | Shadows in conformally related gravity theories |
| title_sort | shadows in conformally related gravity theories |
| url | http://www.sciencedirect.com/science/article/pii/S037026932200243X |
| work_keys_str_mv | AT kunalpal shadowsinconformallyrelatedgravitytheories AT kuntalpal shadowsinconformallyrelatedgravitytheories AT rajibulshaikh shadowsinconformallyrelatedgravitytheories AT tapobratasarkar shadowsinconformallyrelatedgravitytheories |