http://arxiv.org/abs/1811.07917
Anisotropic stresses are ubiquitous in nature, but their modeling in General Relativity is poorly understood and frame-dependent. We introduce the first study on the dynamical properties of anisotropic self-gravitating fluids in a covariant framework. Our description is particularly useful in the context of tests of the black hole paradigm, wherein ultracompact objects are used as black hole mimickers but otherwise lack a proper theoretical framework. We show that: (i) anisotropic stars can be as compact and as massive as black holes, even for very small anisotropies; (ii) the nonlinear dynamics of the 1+1 system is in good agreement with linearized calculations, and shows that configurations below the maximum mass are nonlinearly stable; (iii) strongly anisotropic stars have vanishing tidal Love numbers in the black-hole limit; (iv) their formation will usually be accompanied by gravitational-wave echoes at late times.
G. Raposo, P. Pani, M. Bezares, et. al.
Wed, 21 Nov 18
71/74
Comments: 5+2 pages, 4 figures
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