Colloquium on Oct. 21, 2021

Discovering the Sky at the Longest wavelength

Speaker:Xuelei Chen (NAOC)

Venue:Room 2111, SWIFAR Building

Time:16:00 PM, Thursday, Oct. 21, 2021

Abstract:

After the Big Bang, the Universe entered the so called dark ages, during which structures grow until the first generation of stars, galaxies and black holes formed. The 21cm line of the neutral hydrogen provides a unique probe to the dark ages and cosmic dawn. However, observing the dark age is extremely difficult, not only because there is huge foreground radiation, but because the ionosphere of Earth absorbs and distorts the low frequency radio signal. In fact, the radio band below 30 MHz is the last largely unexplored part of the electromagnetic spectrum. In this talk, I shall present the Discovering Sky at the Longest wavelength (DSL) project, also known as 鸿蒙计划(Hongmeng Project), which aims to unveil the sky at this low frequency and probe the cosmic dawn and dark ages by using an array of microsatellites on lunar orbit. After introducing the conceptual design, I shall also discuss the progress in solving the key technological problems, and the various science cases enabled by such observations.