| Name: | Saurabh Singh |
| Affiliation: | Raman Research Institute |
| Conference ID : | ASI2023_800 |
| Title : | Observing cosmic dawn through 21-cm signal |
| Authors : | Saurabh Singh, Ravi Subrahmanyan, N. Udaya Shankar, Mayuri Sathyanarayana Rao, S. Seetha, K.S. Srivani, B.S. Girish, R. Somashekar, Agaram Raghunathan, Keerthipriya Satish, Yash Agrawal, K. Kavitha |
| Mode of Presentation: | Invited |
| Abstract Category : | General Relativity and Cosmology |
| Abstract : | The emergence of the first stars and galaxies, often termed as cosmic dawn, and subsequent ionization of the Universe constitute crucial epochs in the cosmic timeline. Studying the nature of the first sources of radiation is essential to understanding their evolution. The spin-flip transition from neutral hydrogen, 21-cm signal, constitutes a powerful probe of the early Universe. Tracing its brightness at different cosmological redshifts and spatial scales can unravel several poorly constrained astrophysical properties of the first stars and galaxies and their interaction with the intergalactic medium. However, observing the elusive 21-cm signal from high redshifts is challenging due to multiple factors, which include exceptionally bright foregrounds and instrumental systematics. In this talk, I will discuss some of these challenges and how they are being addressed by experiments worldwide. I will draw examples from SARAS and HERA, 21-cm experiments aiming to detect the global and spatial fluctuations of the 21-cm signal, respectively. I will discuss their calibration techniques, unique systematic and foreground handling approaches, and how proposed space-based observations from PRATUSH can overcome several challenges. I will conclude with the latest results from these experiments, which include inference on the anomalous detection from the EDGES experiment, constraints on the properties of the galaxies in the early Universe, and the improved limits by a joint model for the interferometric and global signal experiments. |
