Constraints on Scalar Spectral Index from Latest Observational Measurements

Understand

Recently, the nine-year data release of the Wilkinson Microwave Anisotropy Probe (WMAP9) found that the inflationary models with the scalar spectral index n_s \geq 1 are excluded at about 5\sigma confidence level.

• In this paper, we set the new limits on the scalar spectral index in different cosmological models combining the WMAP9 data with the small-scale cosmic microwave background measurement from the South Pole Telescope, baryon acoustic oscillation data, Hubble Telescope measurements of the Hubble constant, and supernovae luminosity distance data.
• In most of extended cosmological models, e.g.
• with a dark energy equation of state, the constraints on n_s do not change significantly.