Cross-correlations as a Diagnostic Tool for Primordial Gravitational Waves. (arXiv:2012.03498v2 [astro-ph.CO] UPDATED)

Cross-correlations as a Diagnostic Tool for Primordial Gravitational Waves. (arXiv:2012.03498v2 [astro-ph.CO] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Malhotra_A/0/1/0/all/0/1">Ameek Malhotra</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Dimastrogiovanni_E/0/1/0/all/0/1">Ema Dimastrogiovanni</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Fasiello_M/0/1/0/all/0/1">Matteo Fasiello</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Shiraishi_M/0/1/0/all/0/1">Maresuke Shiraishi</a>

We explore and corroborate, by working out explicit examples, the
effectiveness of cross-correlating stochastic gravitational wave background
anisotropies with CMB temperature fluctuations as a way to establish the
primordial nature of a given gravitational wave signal. We consider the case of
gravitational wave anisotropies induced by scalar-tensor-tensor primordial
non-Gaussianity. Our analysis spans anisotropies exhibiting different angular
behaviours, including a quadrupolar dependence. We calculate the expected
uncertainty on the non-linearity parameter $F_{rm NL}$ obtained as a result of
cross-correlation measurements for several proposed experiments such as the
ground-based Einstein Telescope, Cosmic Explorer, and the space-based Big-Bang
Observer. As a benchmark for future survey planning, we also calculate the
theoretical, cosmic-variance-limited, error on the non-linearity parameter.

We explore and corroborate, by working out explicit examples, the
effectiveness of cross-correlating stochastic gravitational wave background
anisotropies with CMB temperature fluctuations as a way to establish the
primordial nature of a given gravitational wave signal. We consider the case of
gravitational wave anisotropies induced by scalar-tensor-tensor primordial
non-Gaussianity. Our analysis spans anisotropies exhibiting different angular
behaviours, including a quadrupolar dependence. We calculate the expected
uncertainty on the non-linearity parameter $F_{rm NL}$ obtained as a result of
cross-correlation measurements for several proposed experiments such as the
ground-based Einstein Telescope, Cosmic Explorer, and the space-based Big-Bang
Observer. As a benchmark for future survey planning, we also calculate the
theoretical, cosmic-variance-limited, error on the non-linearity parameter.

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