Different cosmological probes, such as primary cosmic microwave background (CMB) anisotropies, CMB lensing, and cosmic shear, are sensitive to the primordial power spectrum (PPS) over different ranges of wave numbers. In this paper, we combine the cosmic shear two-point correlation functions measured from the Subaru Hyper Suprime-Cam (HSC) Year 3 data with the Planck CMB data, and the ACT DR6 CMB lensing data to test modified shapes of the PPS at small scales, while fixing the background cosmology to the flat $\mathrm{\Lambda }\mathrm{CDM}$ model. We consider various types of modifications to the PPS shape: the model with a running spectral index, the tanh-shaped model, the Starobinsky-type modification due to a sharp change in the inflaton potential, the broken power law model, and the multiple broken power law model. Although the HSC cosmic shear data is sensitive to the PPS at small scales, we find that the combined data remains consistent with the standard power law PPS, i.e., the single power law model, for the flat $\mathrm{\Lambda }\mathrm{CDM}$ background. In other words, we conclude that the $S_8$ tension cannot be easily resolved by modifying the PPS within the $\mathrm{\Lambda }\mathrm{CDM}$ background.

Close

PrevNext

View figure in article

• Baryon acoustic oscillations
• Cosmic microwave background
• Cosmological parameters
• Cosmology
• Inflation
• Large scale structure of the Universe