2026/06/20 by Swagat S. Mishra, Umang Kumar, Suratna Das +1 · 1 voice
Physics and Astronomy · #astro-ph.CO #gr-qc #hep-ph #hep-th
Warm inflation is usually expected to completely deplete the inflaton condensate by dissipating its energy into radiation. We show that this expectation fails in a simple and observationally viable regime. In a strongly dissipative warm inflationary scenario, the dissipative ratio, Q=Υ/(3H), can fall rapidly after the end of inflation as the system approaches radiation domination, thereby suppressing further energy transfer to the thermal bath. This leads to a residual inflaton condensate, which subsequently evolves as an effectively non-dissipative scalar field. For potentials with a stable quadratic minimum, this remnant inflaton manifests as a cold dark matter component. We establish this mechanism for the minimal renormalizable potential, with a dissipative coefficient Υ∝ T3. In this case, current cosmological data allow strong dissipation while leaving the inflaton mass weakly constrained by inflationary observables. The observed dark matter abundance then fixes its mass to be m ≈ 0.02 \rm MeV, while larger masses overclose the Universe. The transition to matter-like scaling occurs well before BBN, avoiding a long-lived inflaton dark radiation component. Relic inflaton dark matter therefore turns the post-inflationary dynamics of warm inflation into a new late time constraint on its parameter space.