Paper: astro-ph/0505588
Date: Mon, 30 May 2005 04:29:13 GMT (6kb)

Title: Relic Gravitational Waves and the Evolution of the Universe

Authors: W Zhao
Comments: 6 pages
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In the inflation cosmic models, the relic gravitational waves (RGW) generate
in the inflation stage, and evolve in the universe until now. In the different
cosmic evolution models, one can get different gravitational waves spectrum. In
this paper, we give a simple formula to estimate the spectrum in a general
cosmic model. From this spectrum, one can easily find the relation between the
spectrum and the cosmic models. The spectrum include the information about the
universe evolution from inflation to now. So RGW may be a more useful tool to
research the universe than cosmic microwave background radiation (CMB)

\\ ( http://arXiv.org/abs/astro-ph/0505588 , 6kb)
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Paper: astro-ph/0505589
Date: Mon, 30 May 2005 05:03:33 GMT (128kb)

Title: Numeric Spectrum of Relic Gravitational Waves in Accelerating Universe

Authors: Yang Zhang, Wen Zhao, Yefei Yuan, Tianyang Xia
Comments: 7 pages
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The accelerating expansion of the Universe at the present stage is a process
that will change the spectrum of relic gravitational waves. Here we present a
numerical calculation for the power spectrum of relic gravitational waves in
the accelerating Universe. The results show that although the overall features
of the power spectrum is similar to that in the non-accelerating models, the
amplitude is smaller by an order of $10^{-1}$. We also find that the spectrum
is very sensitive to the index $\beta$ of the inflationary expansion with the
scale factor $a(\tau) \propto |\tau|^{1+\beta}$. With increase of $\beta$, the
resulting spectrum is tilted to be flatter with more power on high frequencies,
and the sensitivity of the second science run of the LIGO detectors puts a
restriction on the parameter $\beta < -1.8$. The influence of reheating
following the inflation has been examined.

\\ ( http://arXiv.org/abs/astro-ph/0505589 , 128kb)