W. M. Keck Observatory press release…
A team of astronomers has used the Subaru Telescope and the W. M. Keck Observatory to discover the most distant galaxy yet, at 12.91 billion light-years from the Earth. This new galaxy, dubbed SXDF-NB1006-2, is slightly farther away than the previous record holder, galaxy GN-108036, which was found last year.
To identify SXDF-NB1006-2, the team used the Subaru Telescope to observe a total of 37 hours in seven nights in two wide fields of the sky. The team, led by Takatoshi Shibuya (The Graduate University for Advanced Studies, Japan), Dr. Nobunari Kashikawa (National Astronomical Observatory of Japan), Dr. Kazuaki Ota (Kyoto University), and Dr. Masanori Iye (National Astronomical Observatory of Japan), carefully processed the images they had obtained. Shibuya measured the color of 58,733 objects in the images and identified four galaxy candidates at a redshift of 7.3, which translates into about 12.9 billion light-years. A careful investigation of the brightness variation of the objects allowed the team to narrow down the number of candidates to two.
Color composite image of the Subaru XMM-Newton Deep Survey Field of galaxy SXDF-NB1006-2, credit NAOJ
Finally, the team needed to make spectroscopic observations to confirm the nature of these candidates. They observed the two galaxy candidates with two spectrographs, the Faint Object Camera and Spectrograph (FOCAS) on the Subaru Telescope and the Deep Imaging Multi-Object Spectrograph (DEIMOS) on the Keck II Telescope, and identified one candidate for which a characteristic emission line of distant galaxies could be detected. The results are slated to be published in the June 20, 2012, edition of Astrophysical Journal.
In addition to locating the galaxy, the team’s research verified that the proportion of neutral hydrogen gas in the 750-million-year-old early Universe was higher than it is today. These findings help to decipher the early Universe during the “cosmic dawn,” when the light of ancient celestial objects and structures first appeared. They concluded that about 80 percent of the hydrogen gas in the ancient Universe, 12.91 billion years ago at a redshift of 7.2, was neutral.
Continue reading “Discovery of the Most Distant Galaxy in the Cosmic Dawn”
