Himiko (Lyman-alpha blob)
Himiko is an astronomical object at a distance of 12.9 billion light years, which was discovered in 2007 by Masami Ouchi with the Subaru Telescope in Hawaii and identified by April 2009 as a Lyman-alpha emitters.
What we see today of Himiko, took place about 800 million years after the Big Bang, so to Reionisierungsepoche. For an object of this era Himiko is unusually large, it plays therefore for the study of the formation of the first galaxies in the early universe an important role.
It was named after the eponymous legendary Japanese empress.
Discovery
The object was supported by a group of Japanese scientists in the XMM -Newton Deep Survey field ( SXDS ) discovered with the Subaru telescope in Hawaii in 2007. In SXDS 207 were found in the optical range, could be the galaxies. Himiko was so bright that the scientists first did not believe in a distant object.
Then the spectrum were studied with the Deep Extragalactic Imaging Multi -Object Spectrograph ( DEIMOS ) on the Keck Observatory in Hawaii and the Inamori Magellan Areal Camera and Spectrograph ( IMACS ) at the Las Campanas Observatory, Chile. It was possible to identify a significant Lyman - α line at a redshift of z = 6.595, which corresponds to an observation period 800 million years after the Big Bang.
With the Spitzer Space Telescope, the United Kingdom Infrared Telescope and other instruments, the star formation rate and the mass of the galaxy were determined.
Description
Himiko is located in the constellation Cetus. Images of the object show a detailed structure, which led to the characterization as a blob ( "blob "). The spectrum shows a significant Lyman α - line resulting from ionized hydrogen gas, and continuous emission of stars.
It is unclear at present, the mechanism by which the hydrogen gas is heated and ionized so that it now radiates in the Lyman - α line. From the data it is assumed that the gas in a galaxy of 17 kpc (or 55,000 light-years ) in diameter, about half the size of our Milky Way. Himiko has a star formation rate of 34 solar masses / year and probably contains 40 billion solar masses. It is uncertain whether the fact that the hydrogen gas is located in the gravitational potential of the galaxy, sufficient to ionize the hydrogen gas, or whether additional mechanisms must be used. Are discussed, for example, heating by an active galactic nucleus ( which would imply the presence of a supermassive black hole ) or the collision of two galaxies.
Planned further research
These possibilities should be confirmed or ruled out by further observations. In particular, should be further investigated the possibility of a black hole with the Keck Observatory, the star formation in Himiko and with the Chandra X-ray Observatory. Even the Hubble Space Telescope could be used to thereby draw the collision of two smaller galaxies as a possibility.