Torsional oscillations of strange stars

Abstract

Abstract. Strange stars are one of the hypothetical compact stellar objects that can be formed after a supernova explosion. The existence of these objects relies on the absolute stability of strange collapsed quark matter with respect to standard nuclear matter. We discuss simple models of strange stars with a bare quark matter surface, thus standard nuclear matter is completely absent. In these models an electric dipole layer a few hundreds Fermi thick should exist close to the star surface. Studying the torsional oscillations of the electrically charged layer we estimate the emitted power, finding that it is of the order of 10 45 erg/s, meaning that these objects would be among the brightest compact sources in the heavens. The associated relaxation times are very uncertain, with values ranging between microseconds and minutes, depending on the crust thickness. Although part of the radiated power should be absorbed by the electrosphere surrounding the strange star, a sizable fraction of photons should escape and be detectable.

Cracking Strange Stars by Torsional Oscillations

“…As it is possible to see, we have two kind of features. There are oscillations whose frequencies depends on a and oscillations with frequencies independent of a [16].…”

“…We have considered a model of a nonbare strange star comprising a quarksphere of superconducting quark matter surmounted by a standard nuclear matter crust [16]. The quarksphere is in two different phases: the CFL phase and the rigid CCSC phase.…”

“…The star composition we have hypothesized in [16] is shown in Figure 1. The inner part of the strange star, called the quarksphere, is populated by deconfined quarks (u, d and s).…”

“…The no-slip condition means that the displacement at the interface of two layers is the same. See [16] for more details on these boundary conditions.…”

“…Indeed, the existence of a phase with a large shear modulus suggests that torsional oscillations of large amplitude can be sustained by this structure. Torsional oscillations of strange stars with a CCSC crust have been first analyzed in [15], while in [16] the coupled oscillations of the CCSC crust and of the ionic crust have been studied. In the present contribution to the proceedings of the CSQCD VI conference we report on the latter study.…”