Constraints on ultra-slow-roll inflation with the NANOGrav 15-Year Dataset

Abstract

Ultra-slow-roll~(USR) inflation predicts an exponential amplification of scalar perturbations at small scales, which leads to a stochastic gravitational wave background~(SGWB) through the coupling of the scalar and tensor modes at the second-order expansion of the Einstein equation. In this work, we search for such a scalar-induced SGWB from the NANOGrav 15-year (NG15) dataset, and find that the SGWB from USR inflation could explain the observed data. The Bayes factors are $54\pm 5$ for the USR inflation model alone and $68\pm 6$ for the combined USR inflation plus supermassive black hole binaries (SMBHB) models. We place constraints on the amplitude of the scalar power spectrum to $P_{\mathrm{Rp}}>10^{-1.95}$ at $95\%$ confidence level (C.L.) at the scale of $k\sim 20{\mathrm{pc}}^{-1}$. We find that ${\log }_{10}{P}_{\mathrm{Rp}}$ degenerates with the peak scale ${\log }_{10}{k}_{\mathrm{p}}$. We also obtain the parameter space allowed by the data in the USR inflationary scenario, where the $e$-folding numbers of the duration of the USR phase has a lower limit $\Delta N>2.80$ ($95\%$ C.L.) when the USR phase ends at $N\approx 20$. With astrophysically motivated priors, the NG15 dataset fits both the USR inflation model and SMBHB model equally well.

16 pages, 7 figures

References in corpus (49)

• The NANOGrav 15-year Data Set: Evidence for a Gravitational-Wave Background
• Search for an isotropic gravitational-wave background with the Parkes Pulsar Timing Array
• Searching for the nano-Hertz stochastic gravitational wave background with the Chinese Pulsar Timing Array Data Release I
• Primordial Black Holes as Dark Matter
• The second data release from the European Pulsar Timing Array III. Search for gravitational wave signals
• The NANOGrav 15-year Data Set: Search for Signals from New Physics
• Primordial Non-Gaussianities from Inflation Models
• The NANOGrav 15-year Data Set: Constraints on Supermassive Black Hole Binaries from the Gravitational Wave Background
• Gravitational waves from a universe filled with primordial black holes
• The recent gravitational wave observation by pulsar timing arrays and primordial black holes: the importance of non-gaussianities
• Generating PBHs and small-scale GWs in two-field models of inflation
• Non-Gaussian tail of the curvature perturbation in stochastic ultra-slow-roll inflation: implications for primordial black hole production
• Primordial gravitational waves in the nano-Hertz regime and PTA data -- towards solving the GW inverse problem
• The power spectrum on small scales: Robust constraints and comparing PBH methodologies
• The Gravitational-Wave Physics II: Progress
• Probing the equation of state of the early Universe with pulsar timing arrays
• Implications for the non-Gaussianity of curvature perturbation from pulsar timing arrays
• The Need For Speed: Rapid Refitting Techniques for Bayesian Spectral Characterization of the Gravitational Wave Background Using PTAs
• Implications of stochastic effects for primordial black hole production in ultra-slow-roll inflation
• The nanohertz stochastic gravitational wave background from cosmic string loops and the abundant high redshift massive galaxies
• Highly non-Gaussian tails and primordial black holes from single-field inflation
• Primordial black holes as dark matter and gravitational waves from bumpy axion inflation
• The Detected Stochastic Gravitational Waves and Subsolar-Mass Primordial Black Holes
• Implications of Pulsar Timing Array Data for Scalar-Induced Gravitational Waves and Primordial Black Holes: Primordial Non-Gaussianity $f_{\mathrm{NL}}$ Considered
• Superheavy quasi-stable strings and walls bounded by strings in the light of NANOGrav 15 year data
• Amplification of Primordial Perturbations from the Rise or Fall of the Inflaton
• One Small Step for an Inflaton, One Giant Leap for Inflation: a novel non-Gaussian tail and primordial black holes
• Constraints on primordial curvature power spectrum with pulsar timing arrays
• Confronting sound speed resonance with pulsar timing arrays
• Primordial black holes and oscillating gravitational waves in slow-roll and slow-climb inflation with an intermediate non-inflationary phase
• Primordial Black Holes Arise When The Inflaton Falls
• Precise WIMP Dark Matter Abundance and Standard Model Thermodynamics
• Features of the inflaton potential and the power spectrum of cosmological perturbations
• Primordial Black Hole Formation in Starobinsky's Linear Potential Model
• Primordial Black Hole Formation in Non-Minimal Curvaton Scenario
• Simultaneously probing the sound speed and equation of state of the early Universe with pulsar timing arrays
• Primordial black holes and scalar-induced gravitational waves from the generalized Brans-Dicke theory
• Scalar induced gravity waves from ultra slow-roll Galileon inflation
• Constraining first-order phase transitions with curvature perturbations
• Implication of nano-Hertz stochastic gravitational wave on dynamical dark matter through a dark first-order phase transition
• Primordial non-Gaussianity as a saviour for PBH overproduction in SIGWs generated by Pulsar Timing Arrays for Galileon inflation
• Primordial black holes and gravitational waves from nonminimally coupled supergravity inflation
• CMB from a Gauss-Bonnet-induced de Sitter fixed point
• Secondary GWs and PBHs in string inflation: formation and detectability
• Implications for primordial black holes from cosmological constraints on scalar-induced gravitational wave
• Unraveling the early universe's equation of state and primordial black hole production with PTA, BBN, and CMB observations
• Primordial black holes from an inflationary potential valley
• Enhanced curvature perturbations from spherical domain walls nucleated during inflation
• Constraints on ultra-slow-roll inflation from the third LIGO-Virgo observing run

Cited by in corpus (1)

• Realisation of the ultra-slow roll phase in Galileon inflation and PBH overproduction