2019-12-13 Abstract
Title: CMB acoustic peak statistics and the excessive shift in the Planck data
Speaker: Lung-Yih Chiang (ASIAA)
Date: December 13 at 15:30
Location: R521, General Building II
Abstract:
Measurement of the acoustic peaks of the cosmic microwave background (CMB) temperature anisotropies has been instrumental in deciding the geometry and content of the universe. Acoustic peak positions vary in different parts of the sky due to statistical fluctuation. I will present the statistics of the peak positions of small patches from ESA Planck data. I found the one containing the mysterious "Cold Spot", an area near the Eridanus constellation where the temperature is significantly lower than Gaussian theory predicts, displays large synchronous shift of peak positions towards smaller multipole numbers with significance lower than one in 10000. For the combined anomalies of large synchronous shifts in acoustic peaks and lower than usual temperature at the Cold Spot area, we propose there is some extra localized unknown energy to stretch out the space in the transverse direction around the Cold Spot area. And in the follow-up investigation, we calculated the total shifts of acoustic peak positions and construct a full-sky peak-shift map, from which we found strong global dipole signal compared with simulations. We discuss the possible origin of the dipole and some other features on the map.