Most accurate Statistical Description of Faint Primordial Galaxies 500 M yrs after Big Bang generated
The University of California, Irvine and Baltimore’s Space Telescope Science Institute team describes its use of a new statistical method to analyze Hubble data of lengthy sky surveys. The method enabled the scientists to parse out signals from the noise in Hubble’s deep-sky images, providing the first estimate of the number of small, primordial galaxies in the early universe. There are close to 10X more of these galaxies than were previously detected in deep Hubble surveys.
The period under investigation is called the “epoch of reionization”, post-Big Bang and a few hundred million years in which a dark universe was dominated by photon-absorbing neutral hydrogen, the epoch of reionization was characterized by a phase transition of hydrogen gas due to the accelerated process of star and galaxy formation. “It’s the furthest back you can study with the Hubble Space Telescope,” Mitchell-Wynne said. Hubble’s cameras utilize charge-coupled devices, high-quality electronic image sensors with data spanning optical and infrared wavelengths. Photons in the infrared spectrum come directly from stars and galaxies.
“CIBER measured the infrared background at two wavelengths, 1.1 and 1.6 microns,” UCI cosmologist Asantha Cooray said. These measurements led the CIBER group to confirm the existence of “intrahalo light” from stars distributed outside galaxies. Prof Cooray said: “We believe it’s true that there is intrahalo light, but we made a new discovery by looking at 5 infrared bands with Hubble. We sort of overlap with CIBER and then go into short optical wavelengths, and we see in addition to intrahalo light a new component – stars and galaxies that formed first in the universe.”
These primordial galaxies were very different from well-defined spiral and disc-shaped galaxies currently visible in the universe. They were more diffuse and populated by giant stars. Cooray noted that more observational proof for his team’s findings will be possible with the launch of the James Webb Space Telescope in 2018.
Another area of research is investigating the same part of the sky in other bands, such as X-rays, using NASA’s Chandra X-ray Observatory. “Could there be X-ray emissions associated with this primordial stuff?” he said. “Theoretical astrophysicists have explained that the earliest stars collapsed really quickly because they were so massive. They didn’t go supernovae and disperse material; they’re actually believed to have collapsed into black holes. We would like to see if there are any X-ray emissions associated with such events.” http://news.uci.edu/press-releases/parsing-photons-in-the-infrared-uci-led-astronomers-uncover-signs-of-earliest-galaxies/
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