Highly compact Proca stars with quartic self-interactions

Abstract

We study self-gravitating bound states of a complex vector field, known as Proca stars, with a new type of quartic-order self-interaction which does not exist in the case of either a complex scalar field or a real vector field. Depending on the sign of the coupling constant, this quartic self-interaction can yield a distinct feature of Proca stars from the previously investigated self-interaction of the vector field. We find that self-gravitating solutions can be so compact that the photon sphere could form. However, we also show that the self-interaction gives rise to a ghost instability for the stars whose compactness is close that for the formation of a photon sphere, which might invalidate the formation of the photon sphere.

14 pages, 6 figures, the version to appear in PRD

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Cited by in corpus (4)

• Radial stability of spherical bosonic stars and critical points
• Self-interactions can (also) destabilize bosonic stars
• Internal symmetry to the rescue: well-posed 1+1 evolution of self-interacting vector fields
• Nontopological Electromagnetic Hedgehogs