Franz E Schunck and Eckehard W Mielke 2003 Class. Quantum Grav. 20 R301 doi:10.1088/0264-9381/20/20/201
Franz E Schunck1 and Eckehard W Mielke2
Show affiliationsThere is accumulating evidence that (fundamental) scalar fields may exist in nature. The gravitational collapse of such a boson cloud would lead to a boson star (BS) as a new type of a compact object. As with white dwarfs and neutron stars, a limiting mass exists similarly, below which a BS is stable against complete gravitational collapse to a black hole.
According to the form of the self-interaction of the basic constituents and spacetime symmetry, we can distinguish mini-, axidilaton, soliton, charged, oscillating and rotating BSs. Their compactness prevents a Newtonian approximation; however, modifications of general relativity, as in the case of Jordan–Brans–Dicke theory as a low-energy limit of strings, would provide them with gravitational memory.
In general, a BS is a compact, completely regular configuration with structured layers due to the anisotropy of scalar matter, an exponentially decreasing 'halo', a critical mass inversely proportional to the constituent mass, an effective radius and a large particle number. Due to the Heisenberg principle, a completely stable branch exists, and as a coherent state, it allows for rotating solutions with quantized angular momentum.
In this review, we concentrate on the fascinating possibilities of detecting the various subtypes of (excited) BSs: possible signals include gravitational redshift and (micro-)lensing, emission of gravitational waves, or, in the case of a giant BS, its dark matter contribution to the rotation curves of galactic halos.
04.40.Dg Relativistic stars: structure, stability, and oscillations
95.30.Sf Relativity and gravitation
95.35.+d Dark matter (stellar, interstellar, galactic, and cosmological)
Issue 20 (21 October 2003)
Received 12 March 2003
Published 16 September 2003
Franz E Schunck and Eckehard W Mielke 2003 Class. Quantum Grav. 20 R301
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