Absorption of the Cosmic Microwave Background (CMB) by the 21-cm line hydrogen line at redshift 17

May 17, 2018
Phillips Auditorium
Haystack / MIT
Abstract: 

A deeper than expected absorption with flattened bottom has been observed using the Experiment to Detect the Global EoR signature (EDGES) instruments located at the Murchison Radio-astronomy Observatory in Western Australia. I will describe the instrument and its calibration and how the performance has been improved over a period of about 12 years leading to detection of the 21_cm absorption at 78 MHz. Absorption of the CMB is expected when the hydrogen spin temperature drops from the CMB temperature to the kinetic temperature as the result of Wouthuysen–Field coupling of the Lyman-Alpha radiation from the early stars. I will discuss the need and prospects for confirmation by other instruments, the future plans of EDGES, list mechanisms which might explain the greater depth and flattened profile and allow time for discussion of these mechanisms.

Event Status: 
Active