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arXiv · 2212.07659

Highly compact Proca stars with quartic self-interactions

Katsuki Aoki·Masato Minamitsuji
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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.

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Katsuki Aoki, Masato Minamitsuji. 2022-12-15. Highly compact Proca stars with quartic self-interactions. https://doi.org/10.1103/physrevd.107.044045

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