Spontaneous vectorization in the presence of vector field coupling to matter

Minamitsuji, Masato

doi:10.48550/arxiv.2003.11885

Cited by 1 publication

(1 citation statement)

References 23 publications

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“…The observational signatures of scalarized solutions [40][41][42][43] and extensions to rotating solutions [38,[44][45][46][47][48][49] have been extensively studied in the literature. The couplings of vector or tensor fields with curvature invariants also give rise to similar phenomena such as spontaneous vectorization, tensorization, and spinorization of relativistic stars [50][51][52][53][54][55][56].…”

Section: Introductionmentioning

confidence: 99%

Spontaneous scalarization of charged stars

Minamitsuji,

Tsujikawa

2021

Preprint

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We study static and spherically symmetric charged stars with a nontrivial profile of the scalar field φ in Einstein-Maxwell-scalar theories. The scalar field is coupled to a U (1) gauge field Aµ with the form −α(φ)Fµν F µν /4, where Fµν = ∂µAν − ∂ν Aµ is the field strength tensor. Analogous to the case of charged black holes, we show that this type of interaction can induce spontaneous scalarization of charged stars under the conditions (dα/dφ)(0) = 0 and (d 2 α/dφ 2 )(0) > 0. For the coupling α(φ) = exp(−βφ 2 /M 2 pl ), where β (< 0) is a coupling constant and M pl is a reduced Planck mass, there is a branch of charged star solutions with a nontrivial profile of φ approaching 0 toward spatial infinity, besides a branch of general relativistic solutions with a vanishing scalar field, i.e., solutions in the Einstein-Maxwell model. As the ratio ρc/ρm between charge density ρc and matter density ρm increases toward its maximum value, the mass M of charged stars in general relativity tends to be enhanced due to the increase of repulsive Coulomb force against gravity. In this regime, the appearance of nontrivial branches induced by negative β of order −1 effectively reduces the Coulomb force for a wide range of central matter densities, leading to charged stars with smaller masses and radii in comparison to those in the general relativistic branch. Our analysis indicates that spontaneous scalarization of stars can be induced not only by the coupling to curvature invariants but also by the scalar-gauge coupling in Einstein gravity.

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