| Name: | Nirupam Roy |
| Affiliation: | Indian Institute of Science (IISc), Bangalore |
| Conference ID : | ASI2024_548 |
| Title : | Detection of HI 21 cm emission from a lensed galaxy about 9 billion years ago |
| Authors : | Arnab Chakraborty 1, Nirupam Roy2 |
| Authors Affiliation: | 1 Mcgill University, Montreal - QC H3A 2T8, Canada.
2 Dept. of Physics, Indian Institute of Science, Bengaluru-560012, India. |
| Mode of Presentation: | Invited |
| Abstract Category : | Galaxies and Cosmology |
| Abstract : | The reservoir of cold atomic neutral hydrogen (HI) gas provides the basic fuel for star formation in a galaxy. Understanding the evolution of galaxies over cosmic time requires knowledge of the cosmic evolution of this neutral gas. The best way to probe the atomic gas content in a galaxy is via the HI 21 cm spectral line emission. However, this signal is extremely faint and difficult to detect from individual galaxies at high redshifts with modern telescopes.
We report the first 5 sigma detection of HI 21 cm emission from a star-forming galaxy at redshift z~1.3 (nearly 9 billion years ago) using upgraded Giant Metrewave Radio Telescope (uGMRT). This is the highest redshift HI detection in emission from an individual galaxy to date. The emission is strongly boosted by the gravitational lens, an early type elliptical galaxy, at redshift z ~ 0.13. The measured HI mass of the galaxy is almost twice the inferred stellar mass of the galaxy, indicating an extended structure of the HI gas inside the galaxy. By fitting two-dimensional Gaussian to the HI signal at the peak of the spectral line, we find the source to be marginally resolved with the position angle consistent with the emission being tangential to the critical curve of the lens mass distribution. These results, for the first time, demonstrate the feasibility of observing high redshift HI in a lensed system with a modest amount of telescope time. The large instantaneous bandwidth of modern receivers in current and next-generation telescopes, such as uGMRT, MeerKAT, SKA1-MID; will detect a large number of lensed HI galaxies and significantly improve our understanding of the cold neutral gas reservoirs, the evolution of the HIMF, and the star to gas mass ratio at high redshifts. |
