Gravitational Waves from Oscillons with Cuspy Potentials

We study the production of gravitational waves during oscillations of the inflaton around the minimum of a cuspy potential after inflation. We find that a cusp in the potential can trigger copious oscillon formation, which sources a characteristic energy spectrum of gravitational waves with double peaks. The discovery of such a double-peak spectrum could test the underlying inflationary physics.

Figure 1

Evolutions of ${\rho }_k$ for cuspy potentials with $p=1$ and $k=1.0\times {10}^{-3}{M}_{\mathrm{pl}}$ (orange), $p=2/3$ and $k=1.0\times {10}^{-5}{M}_{\mathrm{pl}}$ (blue), $p=2/5$ and $k=1.3\times {10}^{-4}{M}_{\mathrm{pl}}$ (green), respectively.

Figure 2

Energy density $\rho$ on a two-dimensional slice through the simulation, when $a(t)=6.13$ (top, left), 6.81 (top, right), 7.43 (bottom, left), and 13.4 (bottom, right), in the linear potential model.

Figure 3

Evolution of the energy density spectrum of the field $\varphi$ for the linear potential. The yellow line corresponds to a turning point $a(t)=7.30$.

Figure 4

Energy spectra of GWs today, predicted by the linear potential with $\lambda =9.7\times {10}^{-44}$ (blue) and $\lambda =1.3\times {10}^{-40}$ (green). The black curve is the expected sensitivity curve of the fifth observing run (O5) of the aLIGO-Virgo detector network.