| Author(s) and Co-Author(s) with Affiliation: Mayuri S Rao(Raman Research Institute, Bengaluru - 560080, India), Saurabh Singh(Raman Research Institute, Bengaluru - 560080, India), Srivani K.S(Raman Research Institute, Bengaluru - 560080, India), Girish B.S(Raman Research Institute, Bengaluru - 560080, India), Narendra S(Raman Research Institute, Bengaluru - 560080, India), Keerthipriya S(Raman Research Institute, Bengaluru - 560080, India), Somashekar R(Raman Research Institute, Bengaluru - 560080, India), Yogen Pranesh(University of Rome Tor Vergata, Rome - 00133, Italy), Bharat Chandra P(Raman Research Institute, Bengaluru - 560080, India), Yash Agrawal(Raman Research Institute, Bengaluru - 560080, India), Jayadev Ashok T(Raman Research Institute, Bengaluru - 560080, India), Amarnath(Raman Research Institute, Bengaluru - 560080, India), Adarsh Kumar Dash(University of Cambridge, Cambridge - CB3 0HE, United Kingdom), Kasturi S(Raman Research Institute, Bengaluru - 560080, India), Madhavi S(Raman Research Institute, Bengaluru - 560080, India), Udaya Shankar N(Raman Research Institute, Bengaluru - 560080, India), Seetha S(Raman Research Institute, Bengaluru - 560080, India) |
| Abstract: Two key events in the evolution of the Universe were the time when the first stars and galaxies formed, known as the Cosmic Dawn (CD), and the epoch over which baryonic matter transitioned from being mostly neutral to almost completely ionized, known as the Epoch of Reionisation (EoR). The 21-cm hyperfine transition of neutral hydrogen, with a rest frequency of 1420 MHz, is a powerful probe to study CD and EoR, with the global or monopole 21-cm signal tracing the average evolution of the gas, and the astrophysics and cosmology of CD and EoR. While the exact timeline is poorly understood, these events are expected to have occurred over cosmological redshifts of 30-6, mapping to redshifted 21-cm frequencies of ~ 40-200 MHz. Detecting this signal with high confidence continues to pose a significant challenge, since the signal is extremely weak with a maximum amplitude of less than 300 mK in brightness temperature and is buried in galactic and extragalactic foregrounds of 100 - 10,000 K.
Probing ReionizATion of the Universe using Signal from Hydrogen (PRATUSH) is a proposed space-based radiometer that aims to detect this sky-averaged 21-cm signal from CD, operating in a frequency range of 55 - 110 MHz. Ground-based experiments are confronted with limitations caused by terrestrial radio frequency interference (RFI), ionosphere-induced chromaticity, and modified antenna response in the presence of objects on the horizon and associated terrains. PRATUSH seeks to operate in orbit around the moon, making scientific observations when in the lunar farside shielded from both Earth and the Sun, alleviating the significant challenges faced by ground-based experiments. In this talk, we will present scientific motivation to detect signals from CD/EoR and highlight some of the latest updates from the integrated laboratory concept model tests for receiver qualification, which reached a sensitivity of 12 mK. |
