Abstract
Abstract
Recent debates around the testability of the inflationary paradigm raise the question of how to model-independently discriminate it from competing scenarios. We argue that a detection of the cosmic graviton background (CGB), the relic radiation from gravitons decoupling around Planck time, would rule out the inflationary paradigm, as realistic inflationary models would dilute the CGB to an unobservable level. The CGB contribution to the effective number of relativistic species, ΔN
eff,g
≈ 0.054, is well within the reach of next-generation cosmological probes. We argue that detecting the high-frequency stochastic gravitational wave background associated to the CGB will be challenging but potentially feasible. We briefly discuss expectations within alternatives to inflation, focusing on bouncing cosmologies and emergent scenarios.
Funder
Isaac Newton Trust
Kavli Foundation
Stiftelsen Blanceflor Boncompagni Ludovisi, född Bildt
University of Cambridge ∣ Homerton College, University of Cambridge
John Templeton Foundation
Gordon and Betty Moore Foundation
Publisher
American Astronomical Society
Subject
Space and Planetary Science,Astronomy and Astrophysics
Cited by
15 articles.
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