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Vaidya geometries and scalar fields with null gradients

Vaidya geometries and scalar fields with null gradients

Authors :
Valerio Faraoni
Andrea Giusti
Bardia H. Fahim
Source :
European Physical Journal C: Particles and Fields, Vol 81, Iss 3, Pp 1-4 (2021)
Publication Year :
2021
Publisher :
SpringerOpen, 2021.

Abstract

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.

Details

Language :
English
ISSN :
14346044 and 14346052
Volume :
81
Issue :
3
Database :
Directory of Open Access Journals
Journal :
European Physical Journal C: Particles and Fields
Publication Type :
Academic Journal
Accession number :
edsdoj.fd4cc251fd1743a99d2bf78dedf8f9c7
Document Type :
article
Full Text :
https://doi.org/10.1140/epjc/s10052-021-09040-9