Search

We investigate the anisotropics in the gravitational wave (GW) background produced at preheating after inflation. Using lattice field theory simulations of a massless preheating model, we show that the GW amplitude depends sensitively on the value of the decay product field x coupled to the inflaton s light during inflation. We find a strong anisotropy in the amplitude of the GW background on large angular scales, the details of which strongly depend on the reheating dynamics. We expect similar conclusions for a wide class of inflationary models with light scalar fields. If future direct detection GW experiments are capable of detecting the GW produced by preheating, they should also be able to detect this effect. This could eventually provide a powerful way to distinguish between different inflationary and preheating scenarios. [ABSTRACT FROM AUTHOR]

Abstract: We present a new and especially powerful signature of cosmic strings and other topological or non-topological defects in the polarization of the cosmic microwave background (CMB). We show that even if defects contribute 1% or less in the CMB temperature anisotropy spectrum, their signature in the local -polarization correlation function at angular scales of tens of arc-minutes is much larger than that due to gravitational waves from inflation, even if the latter contribute with a ratio as big as to the temperature anisotropies. We show that when going from non-local to local -polarization, the ratio of the defect signal-to-noise with respect to the inflationary value increases by about an order of magnitude. Proposed B-polarization experiments, with a good sensitivity on arc-minute scales, may either detect a contribution from topological defects produced after inflation or place stringent limits on them. Already Planck should be able to improve present constraints on defect models by about an order of magnitude, to the level of . A future full-sky experiment like CMBpol, with polarization sensitivities of the order of 1 μK arcmin, will be able to constrain the defect parameter ϵ to less than a few×10−9, depending on the defect model. [Copyright &y& Elsevier]