Implications of pulsar timing arrays for Gauss-Bonnet Inflation

TL;DR

This paper explores how pulsar timing array observations can constrain Gauss-Bonnet inflation models, showing they are compatible with current data and proposing specific models with unique inflationary dynamics.

Contribution

It introduces new constraints on Gauss-Bonnet inflation from PTA data and presents two concrete models demonstrating the viability of the proposed inflationary mechanism.

Findings

PTA data is compatible with Gauss-Bonnet inflation models.

A blue-tilted tensor spectrum can be naturally supported in GB inflation.

Specific conditions on the inflaton potential and GB coupling are derived.

Abstract

Correlated time-of-arrival measurements by pulsar timing arrays (PTAs) have provided a new means of constraining astrophysical or cosmological models that produce a gravitational wave (GW) background. For this work, we discuss the implications of PTA observations for Gauss-Bonnet (GB) inflationary models through the production and propagation of inflationary GWs. We show that our GB inflationary scenario is consistent with present PTA and cosmological data. A blue-tilted tensor power spectrum supported by PTAs can be naturally accommodated in GB inflation. Using observational constraints, we derive general conditions for the inflaton potential and the GB coupling function, suggesting that in GB inflation, the inflaton must climb up the potential before rolling downhill and reaching the end of inflation. We provide two concrete GB inflationary models to demonstrate the viability of this mechanism.