Proca stars: Gravitating Bose–Einstein condensates of massive spin 1 particles

By R. Brito, V. Cardoso, Carlos A. R. Herdeiro, Eugen Radu. 2015

275 citations recorded by the source corpus.

Abstract We establish that massive complex Abelian vector fields (mass μ) can form gravitating solitons, when minimally coupled to Einstein's gravity. Such Proca stars (PSs) have a stationary, everywhere regular and asymptotically flat geometry. The Proca field, however, possesses a harmonic time dependence (frequency w), realizing Wheeler's concept of geons for an Abelian spin 1 field. We obtain PSs with both a spherically symmetric (static) and an axially symmetric (stationary) line element. The latter form a countable number of families labelled by an integer m ∈ Z + . PSs, like (scalar) boson stars, carry a conserved Noether charge, and are akin to the latter in many ways. In particular, both types of stars exist for a limited range of frequencies and there is a maximal ADM mass, M max , attained for an intermediate frequency. For spherically symmetric PSs (rotating PSs with m = 1 , 2 , 3 ), M max ≃ 1.058 M Pl 2 / μ ( M max ≃ 1.568 , 2.337 , 3.247 M Pl 2 / μ ), slightly larger values than those for (mini-)boson stars. We establish perturbative stability for a subset of solutions in the spherical case and anticipate a similar conclusion for fundamental modes in the rotating case. The discovery of PSs opens many avenues of research, reconsidering five decades of work on (scalar) boson stars, in particular as possible dark matter candidates.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/f3b56e941b4a92b1871aa273c929afae0b2253c5

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Citations in the corpus

The imitation game: Proca stars that can mimic the Schwarzschild shadow (2021, methodology): “Setting the self-interactions coupling λP to zero, this model yields mini-PSs as solutions [3, 12,37].”
Superradiance (2015, unknown): “Solutions with complex Proca hair were also constructed and shown to share very similar properties to the solutions presented above [509, 111].”
Kerr black holes with Proca hair (2016, background): “They branch off from the Kerr solutions that can support stationary Proca clouds and reduce to Proca stars [3] when the horizon size vanishes.”
Shadows and strong gravitational lensing: a brief review (2018, background): “This idea will be further reinforced in this section by analysing the gravitational lensing of a particular horizonless UCO: a static Proca star with spherical symmetry [25,64], containing a LR pair with opposite stability.”
Dynamical boson stars (2012, background): “Recently, analogous self-gravitating solutions, made of massive spin 1 particles, have been found in the novel work of Brito, Cardoso, Herdeiro, and Radu [90].”
Dark photon limits: A handbook (2021, background): “the field like a Proca star [213], or ultracold stream [214–217], then”