Constraining ultra-slow roll inflation using cosmological datasets

H.V. Ragavendra

Following the detections of localized and stochastic gravitational waves by LIGO and PTA collaborations respectively, there are several models of early universe that attempt to explain these observations by enhancing primordial scalar power over small scales. A promising candidate amongst them is called ultra slow roll (USR) inflation. In this talk, I shall present our recent work, where we constrain this model against cosmological datasets of cosmic microwave background, galaxy distribution and Lyman-alpha surveys. These datasets over large scales (Giga parsec to Mega parsec range) complement the small scale observational missions (over few parsecs or lesser) mentioned earlier. Our analysis extends the range of scales constrained thus far and improve the bound on the amplitude of the power spectrum. The constraints, especially from Lyman-alpha data, improve upon the existing bounds on primordial power upto scales as small as few kilo parsecs. They in turn inform us about the dynamics of the USR phase, such as its onset and duration, during inflationary epoch. I shall discuss the main results of this analysis and conclude with the outlook of this work.