Lozanov, Kaloian D.Amin, Mustafa A.2019-08-282019-08-282019Lozanov, Kaloian D. and Amin, Mustafa A.. "Gravitational perturbations from oscillons and transients after inflation." <i>Physical Review D,</i> 99, no. 12 (2019) American Physical Society: https://doi.org/10.1103/PhysRevD.99.123504.https://hdl.handle.net/1911/107376We study the scalar and tensor perturbations generated by the fragmentation of the inflaton condensate into oscillons or transients after inflation, using nonlinear classical lattice simulations. Without including the backreaction of metric perturbations, we find that the magnitude of scalar metric perturbations never exceeds a few ×10−3, whereas the maximal strength of the gravitational wave signal today is O(10−9) for standard postinflationary expansion histories. We provide parameter scalings for the α-attractor models of inflation, which can be easily applied to other models. We also discuss the likelihood of primordial black hole formation, as well as conditions under which the gravitational wave signal can be at observationally interesting frequencies and amplitudes. Finally, we provide an upper bound on the frequency of the peak of the gravitational wave signal, which applies to all preheating scenarios.engArticle is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.Journal articlehttps://doi.org/10.1103/PhysRevD.99.123504