Astronomers from McGill College in Canada and the Indian Institute of Science (IISc) in Bengaluru have used knowledge from the Big Metrewave Radio Telescope (GMRT) in Pune to detect a radio sign originating from atomic hydrogen in a particularly distant galaxy.
“The astronomical distance over which such a signal has been picked up is the largest so far by a large margin. This is also the first confirmed detection of strong lensing of 21 cm emission from a galaxy”, in keeping with an IISc assertion.
The findings have been printed in Month-to-month Notices of the Royal Astronomical Society.
Atomic hydrogen is the essential gasoline required for star formation in a galaxy. When sizzling ionised gasoline from the encircling medium of a galaxy falls onto the galaxy, the gasoline cools and types atomic hydrogen, which then turns into molecular hydrogen, and finally results in the formation of stars, it was defined.
“Therefore, understanding the evolution of galaxies over cosmic time requires tracing the evolution of neutral gas at different cosmological epochs”, the assertion mentioned.
Additionally Learn | Closest identified black gap to Earth noticed by astronomers
Atomic hydrogen emits radio waves of 21 cm wavelength, which will be detected utilizing low frequency radio telescopes just like the GMRT. Thus, 21 cm emission is a direct tracer of the atomic gasoline content material in each close by and distant galaxies.
Nevertheless, this radio sign is extraordinarily weak and it’s practically not possible to detect the emission from a distant galaxy utilizing present telescopes because of their restricted sensitivity.
“Until now, the most distant galaxy detected using 21 cm emission was at redshift z=0.376, which corresponds to a look-back time – the time elapsed between detecting the signal and its original emission – of 4.1 billion years (Redshift represents the change in wavelength of the signal depending on the object’s location and movement; a greater value of z indicates a farther object),” it mentioned.
Utilizing GMRT knowledge, Arnab Chakraborty, post-doctoral researcher on the Division of Physics and Trottier Area Institute of McGill College, and Nirupam Roy, Affiliate Professor, Division of Physics, IISc, have detected a radio sign from atomic hydrogen in a distant galaxy at redshift z=1.29.
“Due to the immense distance to the galaxy, the 21 cm emission line had redshifted to 48 cm by the time the signal travelled from the source to the telescope,” says Chakraborty. The sign detected by the staff was emitted from this galaxy when the universe was solely 4.9 billion years outdated; in different phrases, the look-back time for this supply is 8.8 billion years.
This detection was made attainable by a phenomenon known as gravitational lensing, wherein the sunshine emitted by the supply is bent because of the presence of one other huge physique, similar to an early kind elliptical galaxy, between the goal galaxy and the observer, successfully ensuing within the “magnification” of the sign.
“In this specific case, the magnification of the signal was about a factor of 30, allowing us to see through the high redshift universe,” explains Roy.
The staff additionally noticed that the atomic hydrogen mass of this specific galaxy is sort of twice as excessive as its stellar mass. These outcomes display the feasibility of observing atomic gasoline from galaxies at cosmological distances in comparable lensed programs with a modest quantity of observing time. It additionally opens up thrilling new prospects for probing the cosmic evolution of impartial gasoline with current and upcoming low-frequency radio telescopes within the close to future, the assertion mentioned.
Yashwant Gupta, Centre Director at NCRA (Nationwide Centre for Radio Astrophysics), mentioned, “Detecting neutral hydrogen in emission from the distant Universe is extremely challenging and has been one of the key science goals of GMRT. We are happy with this new path-breaking result with the GMRT, and hope that the same can be confirmed and improved upon in the future.”