Colloquium on May. 25, 2023

To detect the 21 cm global spectrum from the Cosmic Dawn: single antenna and interferometer

Speaker: Bin Yue  (NAOC)

Venue: SWIFAR Building 2111

Time: 15:00 PM, Thursday, May. 25, 2023

Abstract:

The 21 cm global spectrum (monopole) from the Cosmic Dawn is a powerful tool to detect the thermal history of the Universe and Pop III stars. Different from the power spectrum that needs large interferometer array to observe, monopole signal can be detected by a single small-aperture and wide-field antenna. Some of these experiments have been constructed on Earth, for example the EDGES, SARAS, and so on, but the measured results are still in debate, mainly because the systematics and the ionospheric effects are hard to perfectly migrated. In future, the space programs, e.g. Hongmeng (DSL), DAPPER, can do better measurements in the lunar-orbit sites. On the other hand, if the beam is anisotropic, AND/OR the sky is non-flat, the monopole also contributes to the interferometer visibility. So an interferometer also has the ability to measure the 21 cm global spectrum. This is kind of independent measurements based on different principle. In this talk, I will review the recent progress in single antenna 21 cm global spectrum observations, and introduce the algorithm of extracting monopole signal from the visibilities, and show some simulated results for some typical array configurations.

Report PPT:  SWIFAR_Bin Yue.pdf