Bound on Photon Circular Orbits in General Relativity and Beyond
The existence of a photon circular orbit can tell us a lot about the nature of the underlying spacetime, since it plays a pivotal role in the understanding of the characteristic signatures of compact objects, namely the quasi-normal modes and shadow radius. For this purpose, determination of the loc...
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| Format: | Article |
| Language: | English |
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MDPI AG
2021-11-01
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| Series: | Galaxies |
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| Online Access: | https://www.mdpi.com/2075-4434/9/4/96 |
| _version_ | 1797504451070656512 |
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| author | Sumanta Chakraborty |
| author_facet | Sumanta Chakraborty |
| author_sort | Sumanta Chakraborty |
| collection | DOAJ |
| description | The existence of a photon circular orbit can tell us a lot about the nature of the underlying spacetime, since it plays a pivotal role in the understanding of the characteristic signatures of compact objects, namely the quasi-normal modes and shadow radius. For this purpose, determination of the location of the photon circular orbit is of utmost importance. In this work, we derive bounds on the location of the photon circular orbit around compact objects within the purview of general relativity and beyond. As we have explicitly demonstrated, contrary to the earlier results in the context of general relativity, the bound on the location of the photon circular orbit is not necessarily an upper bound. Depending on the matter content, it is possible to arrive at a lower bound as well. This has interesting implications for the quasi-normal modes and shadow radius, the two key observables related to the strong field tests of gravity. Besides discussing the bound for higher dimensional general relativity, we have also considered how the bound on the photon circular orbits gets modified in the braneworld scenario, for pure Lovelock and general Lovelock theories of gravity. Implications of these results for compact objects were also discussed. |
| first_indexed | 2024-03-10T04:04:45Z |
| format | Article |
| id | doaj.art-de50855895304804bef601ab7dbf2743 |
| institution | Directory Open Access Journal |
| issn | 2075-4434 |
| language | English |
| last_indexed | 2024-03-10T04:04:45Z |
| publishDate | 2021-11-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Galaxies |
| spelling | doaj.art-de50855895304804bef601ab7dbf27432023-11-23T08:26:08ZengMDPI AGGalaxies2075-44342021-11-01949610.3390/galaxies9040096Bound on Photon Circular Orbits in General Relativity and BeyondSumanta Chakraborty0School of Physical Sciences, Indian Association for the Cultivation of Science, Kolkata 700032, IndiaThe existence of a photon circular orbit can tell us a lot about the nature of the underlying spacetime, since it plays a pivotal role in the understanding of the characteristic signatures of compact objects, namely the quasi-normal modes and shadow radius. For this purpose, determination of the location of the photon circular orbit is of utmost importance. In this work, we derive bounds on the location of the photon circular orbit around compact objects within the purview of general relativity and beyond. As we have explicitly demonstrated, contrary to the earlier results in the context of general relativity, the bound on the location of the photon circular orbit is not necessarily an upper bound. Depending on the matter content, it is possible to arrive at a lower bound as well. This has interesting implications for the quasi-normal modes and shadow radius, the two key observables related to the strong field tests of gravity. Besides discussing the bound for higher dimensional general relativity, we have also considered how the bound on the photon circular orbits gets modified in the braneworld scenario, for pure Lovelock and general Lovelock theories of gravity. Implications of these results for compact objects were also discussed.https://www.mdpi.com/2075-4434/9/4/96photon spherebraneworld scenarioLovelock gravityblack hole shadowquasi-normal modes |
| spellingShingle | Sumanta Chakraborty Bound on Photon Circular Orbits in General Relativity and Beyond Galaxies photon sphere braneworld scenario Lovelock gravity black hole shadow quasi-normal modes |
| title | Bound on Photon Circular Orbits in General Relativity and Beyond |
| title_full | Bound on Photon Circular Orbits in General Relativity and Beyond |
| title_fullStr | Bound on Photon Circular Orbits in General Relativity and Beyond |
| title_full_unstemmed | Bound on Photon Circular Orbits in General Relativity and Beyond |
| title_short | Bound on Photon Circular Orbits in General Relativity and Beyond |
| title_sort | bound on photon circular orbits in general relativity and beyond |
| topic | photon sphere braneworld scenario Lovelock gravity black hole shadow quasi-normal modes |
| url | https://www.mdpi.com/2075-4434/9/4/96 |
| work_keys_str_mv | AT sumantachakraborty boundonphotoncircularorbitsingeneralrelativityandbeyond |