Colloquium on Mar. 30, 2023

Using Ultra-long wavelength to research absorption and distribution of the free electrons

Speaker:Yanping Cong (SHAO)

Venue:SWIFAR Building 2111

Time:15:00 PM, Thursday, Mar. 30, 2023

Abstract:

The radio sky at frequency below ~10 MHz is still largely unknown, and the free-free absorption of low frequency radio waves by thermal electrons in the warm ionized medium of our Galaxy becomes very significant. The upcoming space experiments aiming at such low frequencies (ultra-long wavelength or ultra-low frequency) would benefit from reasonable expectations of the sky brightness distribution at relevant frequencies. In this talk, I will introduce the radio sky model that is valid down to ~1MHz with considering the absorption of discrete HII objected and diffuse component of WIM. The absorption strength depends on the radio frequency, so for the second work, we propose that from these simulated ultralong-wavelength multi-frequency maps, the three-dimensional distribution of the Galactic electrons can be reconstructed. This novel and robust reconstruction of the Galactic electron distribution will be a key science case of those upcoming space missions such as the Discovering Sky at the Longest wavelength (DSL) and Farside Array for Radio Science Investigations of the Dark ages and Exoplanets (FARSIDE) which will produce high-resolution multi-frequency sky maps at the ultralong-wavelength.

Report PPT:SWIFAR_Yanping Cong.pptx