June 23, 2012
Scientists Discover New Submillimeter Galaxy
Using an array of radio telescopes, researchers from Europe and Japan have discovered a submillimeter galaxy -- a type of galaxy that has intense star formation activity and is covered by large amounts of dust -- located approximately 12.4 billion light-years away.
The international team of experts, which was led by Kyoto University Associate Professor Tohru Nagao, used the Atacama Large Millimeter/submillimeter Array (ALMA) in southern Chile to locate the galaxy, the researchers announced in a Thursday press release.
Furthermore, they also detected an emission line from nitrogen in the galaxy, and learned that, even at just 1.3 billion years after the Big Bang, that its elemental composition was similar to that of the present universe.
"This result suggests that intense star formation activities had occurred in the early universe," they said in their statement. "ALMA observes celestial objects at millimeter wavelength, which penetrates though dust clouds. In addition, ALMA also has extraordinary sensitivity, which is capable of catching even extremely faint radio signals. This is the result with one of the most distant galaxies ALMA has ever observed."
Nagao explained that the research team focused their attention on millimeter waves -- radio waves that are the wavelength of approximately one millimeter -- so that they could study the galaxies without being blocked by the dust. In order to accomplish the feat, they used the ALMA international radio astronomy observatory in order to detect the weak signals from the galaxy known as galaxy LESS J0332.
"Nagao and other staff proposed observing a nitrogen emission line from the sub-millimeter galaxy LESS J0332 with ALMA and comparing it with the already detected carbon emission line," they said. "More than 900 proposals from around the globe were submitted to ALMA for its first scientific observation period and reviewed by experts in various astronomical fields. The team led by Nagao finally won the ALMA observation time by surviving the competition with the oversubscription rate of nine."
They analyzed the element abundance of the galaxy, and compared the brightness ratio of the observed emission lines from nitrogen and carbon within the galaxy with existing theoretical calculations. They found that the elemental composition of LESS J0332 is "significantly different" than that of the universe immediately following the Big Bang, especially in terms of the nitrogen content in the newly discovered galaxy.
The early universe was composed of almost entirely hydrogen and helium, and since the emission lines from LESS J0332 took 12.4 billion years to reach Earth, the newfound galaxy is "located in the young universe at 1.3 billion light years after the Big Bang," the research team discovered. Their findings have been published in the "Letters" section of the journal Astronomy & Astrophysics (A&A).
"Submillimeter galaxies are thought to be relatively massive galaxies in the growth phase," Nagano said. "Our research, revealing that LESS J0332 already has an elemental composition similar to the sun, shows us that the chemical evolution of these massive galaxies occurred rapidly made in the early universe, that is to say, in the early universe active star formation occurred for a short period of time."
However, based on their current observations, the researchers cannot tell the galaxy's shape or the spatial distribution of the element composition ratio of the newly discovered galaxy. This is due to a lack of spatial resolution, but the team plans to overcome those issues with additional antennas and improved capabilities, which will improve the resolution and allow Nagano and colleagues to study LESS J0332's inside structure.
Other scientists working on the project include University of Cambridge Professor Roberto Maiolino, European Southern Observatory APEX Project Scientist Carlos De Breuck, University of Leeds Professor Paola Caselli, Bunyo Hatsukade of Kyoto University and the Japan Society for the Promotion of Science, and Kazuya Saigo of the East-Asia ALMA Regional Center, the National Astronomical Observatory of Japan, and the National Institutes of Natural Sciences.