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arXiv · 2004.08459

Dynamical $\ell$-boson stars: generic stability and evidence for non-spherical solutions

Víctor Jaramillo·Nicolas Sanchis-Gual·Juan Barranco·Argelia Bernal·Juan Carlos Degollado·Carlos Herdeiro·Darío Núñez
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Abstract

$\ell$-boson stars are static, spherical, multi-field self-gravitating solitons. They are asymptotically flat, finite energy solutions of Einstein's gravity minimally coupled to an odd number of massive, complex scalar fields. A previous study assessed the stability of $\ell$-boson stars under spherical perturbations, finding that there are both stable and unstable branches of solutions, as for single-field boson stars ($\ell=0$). In this work we probe the stability of $\ell$-boson stars against non-spherical perturbations by performing numerical evolutions of the Einstein-Klein-Gordon system, with a 3D code. For the timescales explored, the $\ell$-boson stars belonging to the spherical stable branch do not exhibit measurable growing modes. We find, however, evidence of zero modes; that is, non-spherical perturbations that neither grow nor decay. This suggests the branching off towards a larger family of equilibrium solutions: we conjecture that $\ell$-boson stars are the enhanced isometry point of a larger family of static (and possibly stationary), non-spherical multi-field self-gravitating solitons.

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Víctor Jaramillo, Nicolas Sanchis-Gual, Juan Barranco, Argelia Bernal, Juan Carlos Degollado, Carlos Herdeiro, Darío Núñez. 2020-04-17. Dynamical $\ell$-boson stars: generic stability and evidence for non-spherical solutions. https://doi.org/10.1103/physrevd.101.124020

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