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arXiv · 2110.04594

The ghost of vector fields in compact stars

Hector O. Silva·Andrew Coates·Fethi M. Ramazanoğlu·Thomas P. Sotiriou
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Abstract

Spontaneous scalarization is a mechanism that allows a scalar field to go undetected in weak gravity environments and yet develop a nontrivial configuration in strongly gravitating systems. At the perturbative level it manifests as a tachyonic instability around spacetimes that solve Einstein's equations. The endpoint of this instability is a nontrivial scalar field configuration that can significantly modify a compact object's structure and can produce observational signatures of the scalar field's presence. Does such a mechanism exists for vector fields? Here we revisit the model that constitutes the most straightforward generalization of the original scalarization model to a vector field and perform a perturbative analysis. We show that a ghost appears as soon as the square of the naive effective mass squared becomes negative anywhere. This result poses a serious obstacle in generalizing spontaneous scalarization to vector fields.

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Hector O. Silva, Andrew Coates, Fethi M. Ramazanoğlu, Thomas P. Sotiriou. 2021-10-09. The ghost of vector fields in compact stars. https://doi.org/10.1103/physrevd.105.024046

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