English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

In a previous paper [1] we considered the possibility that (within theearly-radiation epoch) there has been (also) a short period of a significantpresence of cosmic strings. During this radiation-plus-strings stage theUniverse matter-energy content can be modelled by a two-component fluid,consisting of radiation (dominant) and a cosmic-string fluid (subdominant). Itwas found that, during this stage, the cosmological gravitational waves (CGWs)- that had been produced in an earlier (inflationary) epoch - with comovingwave-numbers below a critical value (which depends on the physics of thecosmic-string network) were filtered, leading to a distorsion in the expected(scale-invariant) CGW power spectrum. In any case, the cosmological evolutiongradually 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 thelate-radiation era through the radiation-plus-strings stage, thetime-dependence of the cosmological scale factor is modified, something thatleads to a discontinuous change of the corresponding scalar curvature, which,in turn, triggers the quantum-mechanical creation of gravitons. In this paperwe discuss several aspects of such a process, and, in particular, theobservational consequences on the expected gravitational-wave (GW) powerspectrum.

Graviton production in the scaling of a long-cosmic-string network