Null energy condition violation during inflation and pulsar timing array observations

Abstract

Recently, evidence of stochastic gravitational wave background (SGWB) signals observed by pulsar timing array (PTA) collaborations, has prompted investigations into their origins. We explore the compatibility of a proposed inflationary scenario, incorporating an intermediate null energy condition (NEC)-violating phase, with the PTA observations. The NEC violation potentially amplifies the primordial tensor power spectrum, offering a promising explanation for PTA observations. Numerical analyses, primarily focused on NANOGrav's 15-year results, reveal the model's compatibility with PTA data. Notably, the model predicts a nearly scale-invariant GW spectrum in the mHz frequency range, which sets our scenario apart from other interpretations predicting a red primordial GW spectrum on smaller scales.

14 pages plus one appendix, 4 figures; match published version; reference added; correct a typo in eq.15

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Cited by in corpus (18)

• Charting the Nanohertz Gravitational Wave Sky with Pulsar Timing Arrays
• Constraining the impact of standard model phase transitions on primordial black holes
• Constraints on Inflation with Null Energy Condition Violation from Advanced LIGO and Advanced Virgo's First Three Observing Runs
• Toward a test of Gaussianity of a gravitational wave background
• Null energy condition violation and beyond Horndeski physics in light of DESI DR2 data
• Constraining string cosmology with the gravitational-wave background using the NANOGrav 15-year data set
• Interpreting Pulsar Timing Array data of Gravitational Waves with Ekpyrosis-Bouncing Cosmology
• Detecting a Gravitational-Wave Background from Inflation with Null Energy Condition Violation: Prospects for Taiji
• NEC violation in $f(\bar{R},\bar{T})$ gravity in the context of a non-canonical theory via modified Raychaudhuri equation
• Parity-violating primordial gravitational waves from null energy condition violation
• Climbing over the potential barrier during inflation via null energy condition violation
• Thermodynamics of a Non-canonical $f(\bar{R},\bar{T})$ gravity
• Gravitational waves in a cyclic Universe: resilience through cycles and vacuum state
• Multimodality in the Search for New Physics in Pulsar Timing Data and the Case of Kination-amplified Gravitational-wave Background from Inflation
• Implications of pulsar timing arrays for Gauss-Bonnet Inflation
• SageNet: Fast Neural Network Emulation of the Stiff-amplified Gravitational Waves from Inflation
• Gravitational Waves from Primordial Black Holes formed by Null Energy Condition Violation during Inflation
• Testing No slip model with pulsar timing arrays: NANOGrav and IPTA