Discovery Of Primitive Triple Galaxies Sheds Light On The Mystery Of Cosmic Dawn
Spotted 13 billion light years away, the trio of galaxies offer a view into earliest stages of the universe.
The discovery of a trio of primitive galaxies in an enormous blob of primordial gas 13 billion light years from Earth sheds light on the mystery of the earliest stages of galaxy formation known as "cosmic dawn."
Astronomers made the discovery using the combined power of NASA's Hubble and Spitzer space telescopes and the Atacama Large Millimeter/submillimeter Array telescope, called ALMA, in Chile, according to NASA.
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"This exceedingly rare triple system, seen when the universe was only 800 million years old, provides important insights into the earliest stages of galaxy formation during a period known as 'cosmic dawn,' when the universe was first bathed in starlight," said Richard Ellis of the California Institute of Technology in Pasadena, who is a member of the research team.
"Even more interesting, these galaxies appear poised to merge into a single massive galaxy, which could eventually evolve into something akin to the Milky Way," said Ellis.
The object was first detected in 2009 and scientists thought it to be a giant bubble of ionized gas, which they named Himiko for a legendary queen of ancient Japan.
"The new observations revealed that, rather than a single galaxy, Himiko harbors three distinct, bright sources, whose intense star formation is heating and ionizing this giant cloud of gas," said University of Tokyo Associate Professor Masami Ouchi, who led the international team of astronomers from Japan and the United States.
Areas with rapid star formation are usually brimming with heavy elements such as carbon, silicon, and oxygen. The stars burst into life relatively briefly, then explode as supernovae, producing a fine dust in the intergalactic medium, according to Astronomy magazine.
The dust becomes heated by ultraviolet radiation from massive newborn stars and then re-radiates at radio wavelengths, said Kotaro Kohno of the University of Tokyo. That radiation was not detected in Himiko, Kohno said.
"Surprisingly, observations with ALMA revealed a complete absence of the signal from carbon, which is rapidly synthesized in young stars," said Ouchi. "Given the sensitivity of ALMA, this is truly remarkable. Exactly how this intense activity can be reconciled with the primitive chemical composition of Himiko is quite puzzling."
Astronomers speculate that a large portion of the gas in Himiko, a mixture of the light elements hydrogen and helium, could be primordial and created in the Big Bang. If that theory is correct, the findings could be a landmark discovery signaling the detection of a primordial galaxy seen during its formation.
Astronomers speculate that a large portion of the gas in Himiko could be primordial, a mixture of the light elements hydrogen and helium, which were created in the Big Bang. If that theory is correct, the findings could be a landmark discovery signaling the detection of a primordial galaxy seen during its formation.
"Astronomers are usually excited when a signal from an object is detected," said Ellis. "But, in this case, it's the absence of a signal from heavy elements that is the most exciting result."
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