The most distant galaxy ever observed

It’s called EGS-zs8-1 and it is a particularly bright object that existed at a time when the Universe was only 670 million years after the Big Bang. The results of this study, obtained with the spectrometer MOSFIRE installed at the telescope Keck-I and published in Astrophysical Journal Letters, provide new clues about the massive primordial galaxies that existed during the period of re-ionization.
An international team of astronomers, led by colleagues at Yale University and the University of California at Santa Cruz, have managed to get a picture of a very distant galaxy, located at a time when the Universe was a ‘ age of only 670 million years, determining accurately the distance. The scientists were able to observe this object particularly bright whose light has been traveling for more than 13 billion years to reach the spectrometer MOSFIRE (Multi-Object Spectrometer for Infra-Red Exploration) installed at the Keck I 10-meter observatory WM Keck located in Hawaii. These observations indicate that it is at the time of the most distant galaxy never revealed, which represents a record. The findings are published in the Astrophysical Journal Letters.


Credit: Oesch et al. 2015

Named with the acronym EGS-zs8-1 and originally included in the list of candidates due to its particular color observed in the images provided by NASA space telescopes Hubble and Spitzer, it is one of the brightest objects in the early Universe and massive. “While we see the galaxy as it was more than 13 billion years ago, in the meantime it has grown to form more than 15 percent of the current mass of the Milky Way,” explains Pascal Oesch of Yale University and author of the study. “In doing so, the Galaxy had only 670 million years. At that time, the universe was very young. ” The data analysis has also allowed to determine the fact that the object is in a phase of high fertility stellar which is about 80 times higher compared to that present in our galaxy.
We must say that there are very few primordial galaxies whose distances have been determined accurately and none of them is younger than EGS-zs8-1. “Every other confirmation adds another piece to the puzzle that tells us how it formed the first generation of galaxies,” says Pieter van Dokkum of Yale University and co-author of the study. “Only the larger telescopes are powerful enough to capture the light of these extremely distant galaxies.” In fact, the discovery was made possible thanks to the instrument MOSFIRE installed at the telescope Keck-I which allows astronomers to examine efficiently many galaxies at a time.
Studying these galaxies so remote, determine their distance and their property is a primary goal for the next decade of astronomy.


Credit: Oesch et al. 2015

Data from EGS-zs8-1 indicate that we are seeing the galaxy at a time when the Universe was subject to important changes: we are talking about the era of re-ionization, when the hydrogen that is distributed between the galaxies was passing by neutral state that ionized. “It seems that the younger stars present in primordial galaxies, as EGS-zs8-1, were the main protagonists of this process of transition, we call re-ionization,” adds Rychard Bouwens of Leiden Observatory and co-author of the study.
But these new observations obtained Keck Observatory, together with those of the Hubble and Spitzer, pose other questions. On the one hand, they tell us that galaxies large size existed during the early epochs of the evolutionary history of the Universe and the other indicate that their physical properties are very different from those of the galaxies we see today. Researchers now have clear evidence that confirms the fact that those colors that are characteristic observed in the images of the Spitzer Space Telescope are due to a rapid formation of young and massive stars that have interacted with the primordial gas that is found in these distant galaxies.

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