Imprints of Primordial Non-Gaussianity on Gravitational Wave Spectrum. (arXiv:1811.09151v1 [astro-ph.CO])
<a href="http://arxiv.org/find/astro-ph/1/au:+Unal_C/0/1/0/all/0/1">Caner Unal</a>

Although Cosmic Microwave Background and Large Scale Structure probe the
largest scales of our universe with ever increasing precision, our knowledge is
still very limited for the smaller physical scales other than the bounds on
Primordial Black Hole (PBH) amount. We show that the statistical properties of
the small scale quantum fluctuations can be probed via the stochastic
gravitational wave background, which is induced as the scalar modes re-enter
the horizon. We found that even if scalar curvature fluctuations have a
subdominant (or mild) non-Gaussian component, these non-Gaussian perturbations
can source a dominant portion of the induced GWs. Moreover, the GWs sourced by
non-Gaussian scalar fluctuations peaks at a higher frequency and this can
result in distinctive observational signatures. If the induced GW background is
detected, but not the signatures arising from the non-Gaussian component of the
scalar fluctuations, $zeta = zeta_G + f_{rm NL} , zeta_G^{2}$, this
translates into stringent bounds on $f_{rm NL}$ depending on the amplitude of
the GW signal.

Although Cosmic Microwave Background and Large Scale Structure probe the
largest scales of our universe with ever increasing precision, our knowledge is
still very limited for the smaller physical scales other than the bounds on
Primordial Black Hole (PBH) amount. We show that the statistical properties of
the small scale quantum fluctuations can be probed via the stochastic
gravitational wave background, which is induced as the scalar modes re-enter
the horizon. We found that even if scalar curvature fluctuations have a
subdominant (or mild) non-Gaussian component, these non-Gaussian perturbations
can source a dominant portion of the induced GWs. Moreover, the GWs sourced by
non-Gaussian scalar fluctuations peaks at a higher frequency and this can
result in distinctive observational signatures. If the induced GW background is
detected, but not the signatures arising from the non-Gaussian component of the
scalar fluctuations, $zeta = zeta_G + f_{rm NL} , zeta_G^{2}$, this
translates into stringent bounds on $f_{rm NL}$ depending on the amplitude of
the GW signal.

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