Unveiling Himiko, mysterious space blob at cosmic dawn Primitive nature revealed by Hubble and ALMA observations
The light from the remarkable giant “space blob” Himiko (named after a legendary queen of ancient Japan) reaches us from a time when the universe was only 800 million years old, corresponding to just 6% of its present age. Himiko was discovered in 2009 by Associate Professor Masami Ouchi of the University of Tokyo’s Institute of Cosmic Ray Research (then Carnegie Fellow at the Carnegie Observatories) using the Subaru telescope on Mauna Kea, Hawaii. At that time Himiko was shown to be a mysterious body consisting of a hot, bright gas cloud extending over 55,000 light years, but its source of energy remained unknown.
Using the Hubble Space Telescope and instruments on the Atacama Large Millimeter/Submillimeter Array (ALMA), Ouchi and his collaborators have explored Himiko’s physical nature. The new observations reveal a complex structure suggestive of a rare triple merger of three galaxies, resulting in violent star formation and which is creating the brilliantly-lit gas cloud. Most surprisingly, the possible absence of heavy chemical elements, which were created after the big bang, indicates Himiko’s primitive nature. The observations provide valuable insight into the earliest stages of galaxy formation at a time termed ‘Cosmic Dawn’ when the Universe was first bathed in starlight.
Masami Ouchi, Richard Ellis, Yoshiaki Ono, Kouichiro Nakanishi, Kotaro Kohno, Rieko Momose, Yasutaka Kurono, M. L. N. Ashby, Kazuhiro Shimasaku, S. P. Willner, G. G. Fazio, Yoichi Tamura, and Daisuke Iono,
“AN INTENSELY STAR-FORMING GALAXY AT Z~7 WITH LOW DUST AND METAL CONTENT REVEALED BY DEEP ALMA AND HST OBSERVATIONS”,
The Astrophysical Journal Online Edition: 2013/12/01(UT), doi: 10.1088/0004-637X/778/2/102.