Exploring the edges of the Universe with Hubble and Spitzer space telescopes: discovery of one of the youngest galaxy in the early Universe.

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An international team of researchers (1) which include Nicolas Laporte, a former PhD student of IRAP, Roser Pello and Frederic Boone, both researchers at the IRAP, has discovered a redshift 8 candidate galaxy behind the A2744 cluster of galaxies, within the “Frontier Fields” Hubble program (NASA / ESA). This discovery will be shortly published within the journal Astronomy & Astrophysics.

Three weeks ago during the 223th meeting of the American Astronomical Society held at Washington D.C. (USA), the Space Telescope Science Institute presented its flagship project for the next 3 years: the HST “Frontier Fields”. Two of the most powerful space telescopes to date, Hubble and Spitzer, will dedicate a large amount of their observing time to observe 6 galaxies clusters, who act as additional lenses and amplify the light from background sources including very faint galaxies up to the edge of the observable Universe. This will allow to study for the first time fainter and younger galaxies in the first billion years of the Universe
The first long exposure image of the cluster Abell 2744, obtained in the last months, is the deepest one obtained so far of a cluster of galaxies and is comparable to the previous Hubble Ultra Deep Field, which is blank region of the sky.  All the Frontier Fields clusters have been carefully selected and are the best for this kind of study. Several groups have  already provided the maps showing the expected light amplification as a function of the position around  the clusters.
Thanks to the graviatational lensing by the cluster, the light of the background galaxies can be magnified up to 20 times or even more. This effect converts in practice the Hubble Space Telescope to an equivalent telescope 20 times larger in diameter or more.
In coordination with the Hubble observations, the Spitzer Space Telescope is also taking very deep exposures of the Frontier Fields. The HST and Spitzer data are available to the whole scientific community since the end of 2013 for scientific analysis.
An international team, led by astronomers from the Instituto de Astrofisica de Canarias (IAC) and La Laguna University (Spain), has just completed the first analysis of the observations of the Abell 2744 cluster,  and has highlighted one of the most distant galaxies known to date which clearly shows already the potential of the HST Frontier Fields. Their results are accepted for publications in the scientific journal Astronomy and Astrophysics Letters, and will be one of the first publications based on the Frontier Fields data.

Discovery of a redshift 8 galaxy within the ‘Frontier Fields” Hubble program.

Thanks to the high data quality of the Hubble and Spitzer images, this group has determined the properties of this young galaxy with a better precision than previous studies of other samples at similar cosmic epochs. This galaxy, named Abell2744 Y1, is about 30 times smaller than our Galaxy, the Milky Way, but producing at least 10 times more stars.
From the Earth, this galaxy is seen as she was 650 million years after the Big-Bang, and provides new constraints on the density and properties of the galaxies in the early Universe. Interestingly, it is one of the brightest ones ever discovered at such young cosmic epochs.
Nicolas Laporte, post-doctoral researcher at the IAC, after a PhD at IRAP (France), and expert in the search for very distant galaxies, welcomes the high quality of the Hubble images:  we expected to find very distant galaxies close to the cluster core, where the light amplification is maximum. However this galaxy is very close to the edge of the image where the light is not strongly amplified. We are really lucky that we could find it in the small field of view of HST. In a related study led by Hakim Atek (EPFL, Laussane) many more galaxies are discussed but not so distant as Abell2744_Y1.
Observations of the Frontier Fields by the Hubble and Spitzer space telescopes are in an early stage but have already shown the exceptional potential of this new project aiming to study the first luminous objects. As it happnened with other HST initiatives on deep fields, many observatories all over the world and in space will join the effort with additional observations of the Frontier Fields, which provide unprecedented scientific legacy for future studies with extremely large telescopes, and the James Webb Space Telescope.

(1) The team is made up with researchers of the Instituto de Astrofísica de Canarias (IAC), the Université de Genève, the Observatoire de Lyon, and the IRAP/OMP.

Further Resources :

Publications :

  • “The first Frontier Fields cluster: 4.5 micron excess in a z ~ 8 galaxy candidate in Abell 2744” par N. Laporte et al., A&A Letters, in press, arXiv1401.8263
  • Atek et al., arXiv1311.7670A

Contacts:

  • Nicolas Laporte: nlaporte@iac.es
  • Roser Pello, roser.pello@irap.omp.eu
  • Frédéric Boone, frederic.boone@irap.omp.eu

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