Astrophysics Seminar

Observations have revealed features in the cosmic microwave background (CMB) that are in mild tension with the standard nearly scale-invariant six-parameter spatially flat lambda cold dark matter model of our Universe. In this talk, we will focus on two such features, namely, power suppression and lensing anomaly. It has been observed that the primordial power spectra with low power at long wavelengths can alleviate the lensing anomaly. Firstly, we will investigate power suppression and the related mitigation of lensing anomaly with the help of phenomenological models, which are simple extensions to nearly scale-invariant power spectra that include running and running of running of the spectral index. We will then discuss the significance of our findings using information criteria. In the latter part of the talk, we will explore the ability of near-ultimate future CMB missions such as ECHO to put tighter constraints on these extended models.

This talk is based on our recent work, arXiv:2504.21386