Stability of l-boson stars under linear perturbations

ALCUBIERRE, MIGUEL; DEGOLLADO, JUAN CARLOS; NÚÑEZ, DARÍO; BARRANCO, JUAN; DIEZ-TEJEDOR, ALBERTO; SARBACH, OLIVIER; BERNAL, ARGELIA; MEGEVAND, MIGUEL

Congreso; 22nd International Conference on General Relativity and Gravitation; 2019

l-boson stars are solutions to the static, spherically symmetric Einstein-Klein-Gordon system fora collection of an arbitrary odd number N of complex scalar fields with an internal U (N ) symmetryand no self-interactions. These solutions are parametrized by an angular momentum numberl = (N − 1)/2, an excitation number n, and a continuous parameter ulc rlated to the centralamplitude of the fields φ(r = 0) = ulc rl. They are regular at every point and possess a finite totalmass. For l = 0 the standard spherically symmetric boson stars are recovered. For l not 0, as in thecase of boson stars, l-boson stars exhibit a mass profile against ulc with a maximum for a specificvalue of ulc = ul∗c . In this work we investigate, using linear perturbation theory, the stability againstsmall radial perturbations of l-boson stars. We compute the eigenfrequecies of the perturbationsfor different values of ulc and we found that configurations with values of ulc to the right of ul∗c areunstable under such perturbations while configurations with values of ulc to the left of ul∗c are stable.