Speaker
Description
The Cosmic Dawn (CD) and the Epoch of Reionisation (EoR) mark two pivotal phases in the thermal and ionisation history of the Universe, driven by the formation of the first stars and galaxies. The redshifted 21-cm hyperfine transition of neutral hydrogen provides a powerful probe of these epochs. The global sky-averaged 21-cm monopole signal traces the mean evolution of the intergalactic medium and sets the baseline for power spectrum measurements from interferometers like SKA. This monopole signal directly constrains the timing, duration, and depth of key transitions during CD and EoR, thereby anchoring the mean brightness temperature evolution and providing physically motivated priors that help break degeneracies in SKA-Low power spectrum analyses. Together, global and fluctuation measurements enable a more complete reconstruction of the astrophysics governing early structure formation. Probing ReionizATion of the Universe using Signal from Hydrogen (PRATUSH) is a proposed space-based radiometer designed to measure the sky-averaged 21-cm signal from CD, operating over 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 an 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 discuss the foreground removal and instrument design philosophy of PRATUSH, rooted in spectral smoothness. We also present the latest results from integrated laboratory concept model tests for receiver qualification, achieving a sensitivity of 3.4 mK at a spectral resolution of 610 kHz.
