Stopover talks

Towards Characterization of the First Stars and Galaxies (and Beyond) with Low-Frequency Radio Observations

by Dr Piyanat Kittiwisit (Arizona State U., U. of of KwaZulu-Natal)

Ursa Major (AstroPark)

Ursa Major




One of the most fundamental questions in astronomy is how the Universe evolved to become the highly structured system of stars and galaxies that we see today. The answer to this question can be largely uncovered in the relatively unexplored periods in the history of the Universe known as the Epoch of Reionization (EoR), where radiation from the first generation of stars and galaxies ionized the neutral hydrogen gas in the intergalactic medium, and its preceding Cosmic Dawn (CD), during which the first stars were formed. The reionization process created “bubbles” of ionized regions around radiating sources that perturbed the matter density distribution and influenced the subsequent formation of stars and galaxies. Exactly how and when reionization occurred are currently up for debate. However, by studying these transformative periods we hope to unravel the underlying astrophysics that governs the formation and evolution of the first stars and galaxies. The most promising probe of the CD/EOR is 21 cm intensity mapping, which aims to create a tomographic map of the neutral hydrogen gas over the epochs by mapping the redshifted 21 cm emission lines of neutral hydrogen with radio interferometers operating at frequencies below 200 MHz. In this talk, I will give an overview on the fundamental of the technique, challenge, and current progress. A significant portion of the talk will be dedicated to discussing statistical detection of the EoR with one-point statistics of 21 cm intensity fluctuations. Other related experiments that utilize low frequency radio observations that might be of interest to the Thai astronomy community will be discussed if time allows.


Speaker's CV