12.07.2015 Views

(ed.). Gravitational waves (IOP, 2001)(422s).

(ed.). Gravitational waves (IOP, 2001)(422s).

(ed.). Gravitational waves (IOP, 2001)(422s).

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

312 Elementary introduction to pre-big bang cosmologylog 10 (Ω G )de Sitter-18 -13 -8 -3 2 7 12log 10 ( Hz)Figure 16.10. Graviton spectra in minimal pre-big bang models.By computing graviton production in this background [32] we find that thespectrum is characteriz<strong>ed</strong> by two branches: a high-frequency branch, for modescrossing the horizon (or ‘hitting’ the barrier) in the string phase, ω > ω s =(aη s ) −1 ; and a low-frequency branch, for modes crossing the horizon in the initialdilaton phase, ω

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!