Gravitational radiation from an axion cloud around a black hole: Superradiant phase

Autor:	Yoshino, Hirotaka, Kodama, Hideo
Rok vydání:	2013
Předmět:	General Relativity and Quantum Cosmology High Energy Physics - Phenomenology High Energy Physics - Theory
Zdroj:	Prog. Theor. Exp. Phys. (2014) 043E02
Druh dokumentu:	Working Paper
DOI:	10.1093/ptep/ptu029
Popis:	Motivated by possible existence of string axions with ultralight masses, we study gravitational radiation from an axion cloud around a rotating black hole (BH). The axion cloud extracts the rotation energy of the BH by superradiant instability, while it loses energy through the emission of gravitational waves (GWs). In this paper, GWs are treated as perturbations on a fixed background spacetime to derive the energy emission rate. We give an analytic approximate formula for the case where axion's Compton wavelength is much larger than the BH radius, and then, present numerical results without approximation. The energy loss rate of the axion cloud through the GW emission turns out to be smaller than the energy gain rate of the axion cloud by superradiant instability until nonlinear self-interactions of axions become important. In particular, an axion bosenova must happen at the last stage of superradiant instability. Comment: 31 pages, 10 figures
Databáze:	arXiv
Externí odkaz:	http://arxiv.org/abs/1312.2326 Zobrazit plný text záznamu View this record from Arxiv