Reheating constraints to inflationary models

Abstract

Evidence from the BICEP2 experiment for a significant gravitational-wave background has focussed attention on inflaton potentials $V(\varphi )\propto {\varphi }^{\alpha }$ with $\alpha =2$ ("chaotic" or "$m^2{\varphi }^2$" inflation) or with smaller values of $\alpha$, as may arise in axion-monodromy models. Here we show that reheating considerations may provide additional constraints to these models. The reheating phase preceding the radiation era is modeled by an effective equation-of-state parameter $w_{\mathrm{re}}$. The canonical reheating scenario is then described by $w_{\mathrm{re}}=0$. The simplest $\alpha =2$ models are consistent with $w_{\mathrm{re}}=0$ for values of $n_s$ well within the current $1\sigma$ range. Models with $\alpha =1$ or $\alpha =2/3$ require a more exotic reheating phase, with $-1/3<w_{\mathrm{re}}<0$, unless $n_s$ falls above the current $1\sigma$ range. Likewise, models with $\alpha =4$ require a physically implausible $w_{\mathrm{re}}>1/3$, unless $n_s$ is close to the lower limit of the $2\sigma$ range. For $m^2{\varphi }^2$ inflation and canonical reheating as a benchmark, we derive a relation ${\log }_{10}\left(T_{\mathrm{re}}/10^6\mathrm{GeV}\right)\simeq 2000(n_s-0.96)$ between the reheat temperature $T_{\mathrm{re}}$ and the scalar spectral index $n_s$. Thus, if $n_s$ is close to its central value, then $T_{\mathrm{re}}\lesssim 10^6$~GeV, just above the electroweak scale. If the reheat temperature is higher, as many theorists may prefer, then the scalar spectral index should be closer to $n_s\simeq 0.965$ (at the pivot scale $k=0.05{\mathrm{Mpc}}^{-1}$), near the upper limit of the $1\sigma$ error range. Improved precision in the measurement of $n_s$ should allow $m^2{\varphi }^2$, axion-monodromy, and ${\varphi }^4$ models to be distinguished, even without precise measurement of $r$, and to test the $m^2{\varphi }^2$ expectation of $n_s\simeq 0.965$.

5 pages, 5 figures. Revised version clarifies the dependence of the result on the pivot scale

References in corpus (9)

• Monodromy in the CMB: Gravity Waves and String Inflation
• Reheating in Inflationary Cosmology: Theory and Applications
• A Gravitational Wave Background from Reheating after Hybrid Inflation
• How accurately can 21 cm tomography constrain cosmology?
• A stochastic background of gravitational waves from hybrid preheating
• Inflation and the Scale Dependent Spectral Index: Prospects and Strategies
• Prospects for direct detection of primordial gravitational waves
• Reheating temperature from the CMB
• The inflationary gravitational-wave background and measurements of the scalar spectral index

Cited by in corpus (44)

• Nonperturbative Dynamics Of Reheating After Inflation: A Review
• Reheating predictions in single field inflation
• Perturbation, Non-Gaussianity and Reheating in a GB-$\alpha$-Attractor Model
• Postinflationary Higgs relaxation and the origin of matter-antimatter asymmetry
• CMB constraints on the inflaton couplings and reheating temperature in $\alpha$-attractor inflation
• Natural Inflation: Consistency with Cosmic Microwave Background Observations of Planck and BICEP2
• Probing reheating with primordial spectrum
• How Well Can Future CMB Missions Constrain Cosmic Inflation?
• ${\varphi }^2$ Inflation at its Endpoint
• Gauss-Bonnet Inflation after Planck2018
• Implications of the B-mode Polarization Measurement for Direct Detection of Inflationary Gravitational Waves
• Inflationary magnetogenesis with reheating phase from higher curvature coupling
• Time-Scales for Nonlinear Processes in Preheating after Multifield Inflation with Nonminimal Couplings
• Constraining the general reheating phase in the $\alpha$-attractor inflationary cosmology
• Reconstructing inflation in scalar-torsion $f(T,\varphi )$ gravity
• Neutralino and gravitino dark matter with low reheating temperature
• Shortcomings of New Parametrizations of Inflation
• Inflationary Constraints on Late Time Modulus Dominated Cosmology
• Reheating predictions in Gravity Theories with Derivative Coupling
• Gravity Waves From Non-Minimal Quadratic Inflation
• Can CMB data constrain the inflationary field range?
• Constraints on Kähler moduli inflation from reheating
• A model-independent fit to Planck and BICEP2 data
• Reheating Constraints on Inflaton, Dark Matter: Swampland Conjecture
• Observational signatures of the parametric amplification of gravitational waves during reheating after inflation
• Lectures on Reheating after Inflation
• Quartic hilltop inflation revisited
• Minimal plateau inflationary cosmologies and constraints from reheating
• TASI 2014 Lectures: The Hunt for Dark Matter
• Gravitational Waves from Preheating in Gauss-Bonnet Inflation
• Numerical study of inflationary preheating with arbitrary power-law potential and a realization of curvaton mechanism
• Low Scale Inflation at High Energy Colliders and Meson Factories
• Preheating constraints in $\alpha$-attractor inflation and Gravitational Waves production
• The History of Inflation from Microwave Background Polarimetry and Laser Interferometry
• Warm inflation with non-comoving scalar field and radiation fluid
• Preheating and Reheating Constraints in Supersymmetric Braneworld Inflation
• Low reheating temperatures in monomial and binomial inflationary potentials
• Reconstruction of $\alpha$-attractor supergravity models of inflation
• Some Aspects of the Tachyon Inflation with Superpotential in Confrontation with Planck2018 Data
• The reheating constraints to natural inflation in Horndeski gravity
• Reheating era in Gauss-Bonnet theories of gravity compatible with the GW170817 event
• Model-independent constraints on inflation and reheating
• Measuring the expansion of the universe
• Testing Inflationary Cosmology