Photon Emissivity of the Electrosphere of Bare Strange Stars

We consider the spectrum, emissivity and flux of the electromagneticradiation emitted by the thin electron layer (the electrosphere) at the surfaceof a bare strange star. In particular, we carefully consider the effect of themultiple and uncorrelated scattering on the radiation spectrum (theLandau-Pomeranchuk-Migdal effect), together with the effect of the strongelectric field at the surface of the star. The presence of the electric fieldstrongly influences the radiation spectrum emitted by the electrosphere. Allthe radiation properties of the electrons in the electrosphere essentiallydepend on the value of the electric potential at the quark star surface. Theeffect of the multiple scattering, which strongly suppresses radiationemission, is important only for the dense layer of the electrosphere situatednear the star's surface and only for high values of the surface electricpotential of the star. Hence a typical bremsstrahlung radiation spectrum, whichcould extend to very low frequencies, could be one of the main observationalsignatures even for low temperature quark stars.Comment: 29 pages, 9 figures, accepted for publication in Ap