Constraining the spatial curvature with cosmic expansion history in a cosmological model with a non-standard sound horizon

Understand

Spatial curvature is one of the most fundamental parameters in our current concordance flat $\Lambda$CDM model of the Universe.

• The goal of this work is to investigate how the constraint on the spatial curvature is affected by an assumption on the sound horizon scale.
• The sound horizon is an essential quantity to use the standard ruler from the Cosmic Microwave Background (CMB) and Baryon Acoustic Oscillations (BAOs).
• As an example, we study the curvature constraint in an axion-like Early Dark Energy (EDE) model in light of recent cosmological datasets from Planck, the South Pole Telescope (SPT), and the Atacama Cosmology Telescope (ACT), as well as BAO data compiled in Sloan Digital Sky Survey Data Release 16.