A group of astronomers led by Dr. Ximena Fernandez from Rutgers, the State University of New Jersey, has pushed the limits of radio astronomy to detect a signal emitted by atomic hydrogen gas in an extremely distant star-forming galaxy.
False-color Hubble image of the star-forming spiral galaxy J100054 (center). Image credit: Ximena Fernandez et al.
As the most abundant element in the Universe and the raw fuel for creating stars, hydrogen is used by radio astronomers to detect and understand the makeup of galaxies.
However, until now, radio telescopes have only been able to detect the emission signature of hydrogen from relatively nearby galaxies.
Dr. Fernandez and her colleagues observed radio emission from atomic hydrogen in LIRG COSMOS J100054.83+023126.2 (J100054 for short), a starburst spiral galaxy about 5 billion light-years away – almost double the previous record.
The detection was made using the Karl G. Jansky Very Large Array (VLA) radio telescope at the National Radio Astronomy Observatory, as part of the COSMOS HI Large Extragalactic Survey (CHILES).
The astronomers also found that J100054 would have contained billions of young, massive stars surrounded by clouds of hydrogen gas.
“Due to the upgrade of the VLA, this is the first time we’ve been able to directly measure atomic hydrogen in a galaxy this far from Earth,” Dr. Fernandez said.
“These signals would have begun their journey before our planet even existed, and after 5 billion years of traveling through space without hitting anything, they’ve fallen into the telescope and allowed us to see J100054 for the very first time.”
The previous record was set in 2014 when Swinburne University astronomers used the Arecibo radio telescope in Puerto Rico to detect atomic hydrogen in a galaxy about 3 billion light-years away.
“Our current understanding of galaxy evolution still has many uncertainties associated with the details of gas accretion, processing, and removal across cosmic time,” Dr. Fernandez and co-authors said.
“The next generation of radio telescopes will image the neutral hydrogen in galaxies over large volumes at high redshifts, which will provide key insights into these processes.”
The results will be published this week in the Astrophysical Journal Letters, but have been published on arXiv.org ahead of time.
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Ximena Fernandez et al. Highest Redshift Image of Neutral Hydrogen in Emission: A CHILES Detection of a Starbursting Galaxy at z=0.376. ApJL, accepted for publication; arXiv: 1606.00013
