Broken blue-tilted inflationary gravitational waves: a joint analysis of NANOGrav 15-year and BICEP/Keck 2018 data

• DOI: 10.48550/arxiv.2307.15547
• Publication Date: 2023-01-01
• Authors: Jun-Qian Jiang; Yong Cai; Gen Ye; Yun-Song Piao
• Keywords: High Energy Physics - Theory; Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Theory (hep-th); 0103 physical sciences; FOS: Physical sciences; General Relativity and Quantum Cosmology (gr-qc); 01 natural sciences; General Relativity and Quantum Cosmology; Astrophysics - Cosmology and Nongalactic Astrophysics

Recently, the pulsar timing array (PTA) collaborations have reported evidence for a stochastic gravitational wave background (SGWB) at nano-Hertz band. The spectrum of inflationary (IGW) is unknown, which might exhibit different power law frequency-bands, thus if PTA signal primordial, it will be significant to explore underlying implications current and CMB data on IGW. In this paper, we perform joint Markov Chain Monte Carlo analysis broken power-law IGW with NANOGrav 15-year BICEP/Keck 2018 data. It found that though bestfit spectral tilt band $n^\text{PTA}_\text{T} =2.42^{+0.32}_{-0.91}$, $n^\text{CMB}_\text{T} =0.55^{+0.37}_{-0.10}$ while detectable amplitude $r$ \simeq 0$ still compatible. implication our results inflation also discussed.