![]() “FRBs might be-might be-just this generic phenomenon associated with a whole range of possible sources,” says Cornell University astronomer Shami Chatterjee, who studies the bursts but is not part of the discovery team. They’re also moving toward the conclusion that maybe, as with many other celestial phenomena, there are multiple ways to cook up a fast radio burst. Scientists are struggling to explain the cosmic anachronism. “This is definitely not a place fast radio bursts are expected to live,” Bryan Gaensler, an astronomer at the University of Toronto and a co-author of the new paper, posted on Twitter. Finding this burst among a cluster of aging stars is kind of like finding a smartphone embedded in Stonehenge-the observation doesn’t make sense. Based on observations to date, scientists surmised that the bursts are powered by young, short-lived cosmic objects called magnetars.īut a fast radio burst discovered last year has now been traced to a globular cluster about 11.7 million light-years away, near the neighboring spiral galaxy M81, according to a paper describing the discovery posted on the scientific preprint server arXiv. Often originating billions of light-years away, the extremely bright, extremely brief bursts of radio waves known as fast radio bursts, or FRBs, have defied explanation since they were first spotted in 2007. ![]() The repeating bursts of energy seem to be coming from an ancient group of stars called a globular cluster, which is among the last places astronomers expected to find them. "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.Bright, fleeting blasts of radio waves coming from the vicinity of a nearby galaxy are deepening one of astronomy’s biggest mysteries. This detection was made possible by a phenomenon called gravitational lensing, 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 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. "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. Using GMRT data, Arnab Chakraborty, a post-doctoral researcher at the Department of Physics and Trottier Space Institute of McGill University, and Nirupam Roy, Associate Professor, the Department of Physics, IISc, have detected a radio signal from atomic hydrogen in a distant galaxy at redshift z=1.29. "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 said. However, this radio signal is extremely weak and it is nearly impossible to detect the emission from a distant galaxy using current telescopes due to their limited sensitivity. Thus, 21 cm emission is a direct tracer of the atomic gas content in both nearby and distant galaxies, the PTI report said. "Therefore, understanding the evolution of galaxies over cosmic time requires tracing the evolution of neutral gas at different cosmological epochs", the statement said.Ītomic hydrogen emits radio waves of 21 cm wavelength, which can be detected using low-frequency radio telescopes like the GMRT. ![]() When hot ionised gas from the surrounding medium of a galaxy falls onto the galaxy, the gas cools and forms atomic hydrogen, which then becomes molecular hydrogen, and eventually leads to the formation of stars, it was explained. ![]() The findings have been published in Monthly Notices of the Royal Astronomical Society.Ītomic hydrogen is the basic fuel required for star formation in a galaxy.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |