Scalar field as a null dust
Abstract
We show that a canonical, minimally coupled scalar field which is non-self interacting and massless is equivalent to a null dust fluid (whether it is a test or a gravitating field), in a spacetime region in which its gradient is null. Under similar conditions, the gravitating and nonminimally coupled Brans-Dicke-like scalar of scalar-tensor gravity, instead, cannot be represented as a null dust unless its gradient is also a Killing vector field.
- Publication:
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European Physical Journal C
- Pub Date:
- April 2019
- DOI:
- 10.1140/epjc/s10052-019-6829-x
- arXiv:
- arXiv:1812.06457
- Bibcode:
- 2019EPJC...79..318F
- Keywords:
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- General Relativity and Quantum Cosmology
- E-Print:
- doi:10.1140/epjc/s10052-019-6829-x