Maximum starburst in the early Universe
Sen—Astronomers have discovered a galaxy from the very early Universe turning gas and dust into stars more than 2,000 times faster than our own Milky Way.
The galaxy, HFLS3, was observed when the Universe was only 880 million years old. Light from the galaxy has taken almost 13 billion years to reach us, meaning the observations are based on events less than a billion years after the Big Bang.
The star factory was discovered by astronomers using data from the European Space Agency's Herschel space telescope which observes the Universe in the far-infrared spectrum. It is the earliest starburst galaxy discovered so far.
Whilst the Milky Way churns out stars at the rate of one solar mass per year, HFLS3 is producing the equivalent of 2,900 suns per year. This rapid star formation rate has been dubbed 'maximum starburst'.
Dominik Riechers who led the investigation, said: “Early starbursts like HFLS3 produced the heavy elements that made up later generations of stars and galaxies, and much of the matter we know today.”
The astronomers studying the data were able to translate the HFLS3's infrared brightness into a star formation rate. They had not expected to find such a large and productive galaxy so soon after the formation of the Universe. Current galaxy formation theory suggests that the first galaxies were small and produced stars at a modest rate, and the Universe was about 2 billion years old before larger galaxies with more productive star formation rates - called starburst galaxies - were formed. The observations of HFLS3 could challenge such galaxy formation theories.
“With these observations, Herschel has found a rare example of a galaxy bursting with stars at a time in cosmic history when there were very few such galaxies,” observed Göran Pilbratt, ESA’s Herschel Project Scientist.
Professor Jamie Bock of the California Institute of Technology and a co-author of the study, said: "This galaxy is just one spectacular example, but it's telling us that extremely vigorous star formation is possible early in the universe."
The study, entitled "A Dust-Obscured Massive Maximum-Starburst Galaxy at a Redshift of 6.34" is published in the April 18 issue of Nature.
With a diametre of 3.5 metres, Herschel's primary mirror is the largest of any space telescope, almost one and a half times larger than Hubble. The spacecraft itself measures about 7.5 metres by 4 metres.
The Herschel telescope was launched on May 14, 2009, along with ESA's Planck cosmic background observatory. Both were lifted into space aboard an Ariane 5 rocket from ESA's spaceport in Kourou, French Guiana.
Herschel's mission objective has been to study the origin and evolution of stars and galaxies and in so doing to provide a better understanding of the evolution of the Universe.
Herschel orbits the second Lagrange point ("L2") which is 1.5 million km from the Earth's night side. It was placed in such an orbit to prevent heat from Earth and the Sun interfering with its instruments which need to be operated at a temperature close to absolute zero by a cryogenic system.
Built to last at least three years, the space telescope will operate until the cryogenic system runs out of helium which is expected to be at some point this year.