Astronomers from McGill University in Canada and the Indian Institute of Science (IISc) in Bengaluru have used data from the Giant Metrewave Radio Telescope (GMRT) in Pune to detect a radio signal originating from atomic hydrogen in an extremely distant galaxy.
Key points
- The signal detected by the team was emitted from this galaxy when the universe was only 4.9 billion years old; in other words, the look-back time for this source is 8.8 billion years.
- A lookback time is the time between the light being emitted and being detected.
- Using GMRT data, researchers have detected a radio signal from atomic hydrogen in a distant galaxy at redshift z=1.29.
- This detection was made possible by a phenomenon called gravitational lensing. The gravitational lensing is a phenomenon in which the light emitted by the source is bent due to the presence of another massive body, such as an early type elliptical galaxy, between the target galaxy and the observer, effectively resulting in the magnification of the signal.
- The team also observed that the atomic hydrogen mass of this particular galaxy is almost twice as high as its stellar mass.
- These results demonstrate the feasibility of observing atomic gas from galaxies at cosmological distances in similar lensed systems with a modest amount of observing time.
- The new findings open up exciting new possibilities for probing the cosmic evolution of neutral gas with existing and upcoming low-frequency radio telescopes in the near future.
- Hydrogen is a key building block of the cosmos. Whether stripped down to its charged core, or piled into a molecule, the nature of its presence can tell you a lot about the Universe’s features on the largest of scales.
- Atomic hydrogen is formed as hot, ionized gas from the surroundings of a galaxy starts to fall onto the galaxy, cooling down along the way. Eventually, it turns into molecular hydrogen, and then into stars.
(Source: The Hindu)
