Cosmological imprints of string axions in plateau

Abstract

We initiate a study on various cosmological imprints of string axions whose scalar potentials have plateau regions. In such cases, we show that a delayed onset of oscillation generically leads to a parametric resonance instability. In particular, for ultralight axions, the parametric resonance can enhance the power spectrum slightly below the Jeans scale, alleviating the tension with the Lyman $\alpha$ forest observations. We also argue that a long-lasting resonance can lead to an emission of gravitational waves at the frequency bands which are detectable by gravitational wave interferometers and pulsar timing arrays.

5 pages, 5 figures; v2: references added, v3: matches with the published version

References in corpus (6)

• Ultralight scalars as cosmological dark matter
• Nonperturbative Dynamics Of Reheating After Inflation: A Review
• First constraints on fuzzy dark matter from Lyman-$\alpha$ forest data and hydrodynamical simulations
• Flat-top oscillons in an expanding universe
• Cosmological Perturbations of Extreme Axion in the Radiation Era
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• Kinetic Axion $F(R)$ Gravity Inflation
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• Gravitational Wave Echo of Relaxion Trapping
• Resonant magnetogenesis from axions
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• New scenario of QCD axion clump formation I: Linear analysis
• The Linear Regime of Tachyonic Preheating
• Enhanced Early Galaxy Formation in JWST from Axion Dark Matter?
• Kinetic Axion Dark Matter in String Corrected $f(R)$ Gravity
• $R^2$ Gravity Effects on the Kinetic Axion Phase Space
• Real-time dynamics of axion particle production due to spontaneous decay of a coherent axion field