Gravitational waves from Abelian gauge fields and cosmic strings at preheating

Abstract

Primordial gravitational waves provide a very important stochastic background that could be detected soon with interferometric gravitational wave antennas or indirectly via the induced patterns in the polarization anisotropies of the cosmic microwave background. The detection of these waves will open a new window into the early Universe, and therefore it is important to characterize in detail all possible sources of primordial gravitational waves. In this paper we develop theoretical and numerical methods to study the production of gravitational waves from out-of-equilibrium gauge fields at preheating. We then consider models of preheating after hybrid inflation, where the symmetry breaking field is charged under a local Uð1Þ symmetry. We analyze in detail the dynamics of the system in both momentum and configuration space. We show that gauge fields leave specific imprints in the resulting gravitational wave spectra, mainly through the appearance of new peaks at characteristic frequencies that are related to the mass scales in the problem. We also show how these new features in the spectra correlate with stringlike spatial configurations in both the Higgs and gauge fields that arise due to the appearance of topological winding numbers of the Higgs around Nielsen-Olesen strings. We study in detail the time evolution of the spectrum of gauge fields and gravitational waves as these strings evolve and decay before entering a turbulent regime where the gravitational wave energy density saturates.

Nonperturbative dynamics of reheating after inflation: A review

“…A number of authors have considered lattice simulations of reheating involving Abelian gauge fields [133][134][135] and non-Abelian gauge fields…”

Grand unification and subcritical hybrid inflation

“…The initial conditions for the waterfall field are obtained by considering the tachyonic growth of its quantum fluctuations [23][24][25][26] close to the critical point φ c ,…”

On the transverse-traceless projection in lattice simulations of gravitational wave production

“…[3][4][5] for details. A similar behavior occurs also in the context of gauge fields [7,[27][28][29][30][31]. That the overall shape and final amplitude 4 of the GW spectra does not change much when using the new lattice-based projectors, might seem at first sight surprising, given the fact that the degree of transversality changes several orders of magnitude when replacing the continuum-based projector by the lattice-based ones.…”

“…(1.6), and in the transverse-traceless projection (1.7) itself. Ideally one should use a consistent choice of a lattice derivative everywhere, but in some cases there are restrictions that make this very difficult, for example when dealing with gauge fields [7]. It is enough in any case to have a consistent choice among Eqs.…”