Graviton production in the scaling of a long-cosmic-string network
Abstract
In a previous paper [K. Kleidis, D. B. Papadopoulos, E. Verdaguer, and L. Vlahos, Phys. Rev. DPRVDAQ1550-7998 78, 024027 (2008).10.1103/PhysRevD.78.024027] we considered the possibility that (within the early-radiation epoch) there has been (also) a short period of a significant presence of cosmic strings. During this radiation-plus-strings stage the Universe matter-energy content can be modeled by a two-component fluid, consisting of radiation (dominant) and a cosmic-string fluid (subdominant). It was found that, during this stage, the cosmological gravitational waves—that had been produced in an earlier (inflationary) epoch—with comoving wave numbers below a critical value (which depends on the physics of the cosmic-string network) were filtered, leading to a distorsion in the expected (scale-invariant) cosmological gravitational wave power spectrum. In any case, the cosmological evolution gradually results in the scaling of any long-cosmic-string network and, hence, after a short time interval, the Universe enters into the late-radiation era. However, along the transition from an early-radiation epoch to the late-radiation era through the radiation-plus-strings stage, the time dependence of the cosmological scale factor is modified, something that leads to a discontinuous change of the corresponding scalar curvature, which, in turn, triggers the quantum-mechanical creation of gravitons. In this paper we discuss several aspects of such a process, and, in particular, the observational consequences on the expected gravitational-wave power spectrum.
- Publication:
-
Physical Review D
- Pub Date:
- December 2011
- DOI:
- 10.1103/PhysRevD.84.124044
- arXiv:
- arXiv:1112.2077
- Bibcode:
- 2011PhRvD..84l4044K
- Keywords:
-
- 04.30.-w;
- 11.25.-w;
- 98.80.Cq;
- Gravitational waves: theory;
- Strings and branes;
- Particle-theory and field-theory models of the early Universe;
- High Energy Physics - Theory;
- General Relativity and Quantum Cosmology;
- 83C35;
- 83E30;
- 83C45;
- 81T20
- E-Print:
- 12 pages, 2 figures, accepted for publication in Physical Review D