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Null energy condition violation during inflation and pulsar timing array observations

Published 17 Dec 2023 in gr-qc, astro-ph.CO, and hep-th | (2312.10685v4)

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.

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Authors (3)

  1. Gen Ye 
  2. Mian Zhu 
  3. Yong Cai 

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