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arXiv · 2307.08552

Scalar-induced gravitational wave interpretation of PTA data: the role of scalar fluctuation propagation speed

Shyam Balaji·Guillem Domènech·Gabriele Franciolini
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Abstract

Pulsar timing arrays gathered evidence of the presence of a gravitational wave background around nHz frequencies. If the gravitational wave background was induced by large and Gaussian primordial fluctuations, they would then produce too many sub-solar mass primordial black holes. We show that if at the time of gravitational wave generation the universe was dominated by a canonical scalar field, with the same equation of state as standard radiation but a higher propagation speed of fluctuations, one can explain the gravitational wave background with a primordial black hole counterpart consistent with observations. Lastly, we discuss possible ways to test this model with future gravitational wave detectors.

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Shyam Balaji, Guillem Domènech, Gabriele Franciolini. 2023-07-17. Scalar-induced gravitational wave interpretation of PTA data: the role of scalar fluctuation propagation speed. https://arxiv.org/abs/2307.08552

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