Vaidya geometries and scalar fields with null gradients
Abstract Since, in Einstein gravity, a massless scalar field with lightlike gradient behaves as a null dust, one could expect that it can act as the matter source of Vaidya geometries. We show that this is impossible because the Klein–Gordon equation forces the null geodesic congruence tangent to th...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
SpringerOpen
2021-03-01
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| Series: | European Physical Journal C: Particles and Fields |
| Online Access: | https://doi.org/10.1140/epjc/s10052-021-09040-9 |
| _version_ | 1818610696104968192 |
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| author | Valerio Faraoni Andrea Giusti Bardia H. Fahim |
| author_facet | Valerio Faraoni Andrea Giusti Bardia H. Fahim |
| author_sort | Valerio Faraoni |
| collection | DOAJ |
| description | Abstract Since, in Einstein gravity, a massless scalar field with lightlike gradient behaves as a null dust, one could expect that it can act as the matter source of Vaidya geometries. We show that this is impossible because the Klein–Gordon equation forces the null geodesic congruence tangent to the scalar field gradient to have zero expansion, contradicting a basic property of Vaidya solutions. By contrast, exact plane waves travelling at light speed and sourced by a scalar field acting as a null dust are possible. |
| first_indexed | 2024-12-16T15:18:32Z |
| format | Article |
| id | doaj.art-fd4cc251fd1743a99d2bf78dedf8f9c7 |
| institution | Directory Open Access Journal |
| issn | 1434-6044 1434-6052 |
| language | English |
| last_indexed | 2024-12-16T15:18:32Z |
| publishDate | 2021-03-01 |
| publisher | SpringerOpen |
| record_format | Article |
| series | European Physical Journal C: Particles and Fields |
| spelling | doaj.art-fd4cc251fd1743a99d2bf78dedf8f9c72022-12-21T22:26:44ZengSpringerOpenEuropean Physical Journal C: Particles and Fields1434-60441434-60522021-03-018131410.1140/epjc/s10052-021-09040-9Vaidya geometries and scalar fields with null gradientsValerio Faraoni0Andrea Giusti1Bardia H. Fahim2Department of Physics and Astronomy, Bishop’s UniversityDepartment of Physics and Astronomy, Bishop’s UniversityDepartment of Physics and Astronomy, Bishop’s UniversityAbstract Since, in Einstein gravity, a massless scalar field with lightlike gradient behaves as a null dust, one could expect that it can act as the matter source of Vaidya geometries. We show that this is impossible because the Klein–Gordon equation forces the null geodesic congruence tangent to the scalar field gradient to have zero expansion, contradicting a basic property of Vaidya solutions. By contrast, exact plane waves travelling at light speed and sourced by a scalar field acting as a null dust are possible.https://doi.org/10.1140/epjc/s10052-021-09040-9 |
| spellingShingle | Valerio Faraoni Andrea Giusti Bardia H. Fahim Vaidya geometries and scalar fields with null gradients European Physical Journal C: Particles and Fields |
| title | Vaidya geometries and scalar fields with null gradients |
| title_full | Vaidya geometries and scalar fields with null gradients |
| title_fullStr | Vaidya geometries and scalar fields with null gradients |
| title_full_unstemmed | Vaidya geometries and scalar fields with null gradients |
| title_short | Vaidya geometries and scalar fields with null gradients |
| title_sort | vaidya geometries and scalar fields with null gradients |
| url | https://doi.org/10.1140/epjc/s10052-021-09040-9 |
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