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NASA Spot Distant Galaxy Group Driving Ancient Cosmic Makeover

An international team of NASA astronomers funded in part by NASA has found the farthest galaxy group identified to date.
This transformed the dark, light quenching early cosmos into the one we see around today.
Called EGS77, the trio of galaxies dates to a time when the universe was only 680 million years old, or less than 5% of its current age of 13.8
More significantly, observations show that the galaxies are participants in a sweeping cosmic makeover called reionization.
The era began when light from the first stars changed the nature of the hydrogen throughout the universe in a manner akin to a frozen lake melting in the spring.
Video Source : NASA

This animation shows EGS77’s place in cosmic history, flies to the galaxies, and illustrates how ultraviolet light from their stars create bubbles of ionized hydrogen around them. Credits: NASA’s Goddard Space Flight Center

The young universe was filled with the hydrogen atoms, which so attenuate ultraviolet light that they block our view of early galaxies, said by James Rhoads at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, who is presented the findings on January. 5 at the 235th meeting of the American Astronomical Society is in Honolulu. EGS77 is the first galaxy group who caught in the act of clearing out this cosmic fog.
The more distant individual galaxies have been observed, EGS77 farthest galaxy group to date showing the specific wavelengths of far ultraviolet light revealed by reionization. This emission, called Lyman alpha light, prominent in all members of EGS77.
In its earliest phase, the universe was a glowing plasma of particles including electron, proton, atomic nuclei, and light. Atoms could not yet exist. The universe was is in an ionized state, similar to the gas inside a lighted neon sign or fluorescent tube.
After universe expanded and cooled for about 380,000 years, electrons and protons combined into the first atoms — more than 90% of them hydrogen. Hundreds of millions of years later, Gas formed the first stars and galaxies. But very presence of this abundant gas poses challenges for spotting galaxies in the early universe.  
Hydrogen atoms readily absorb and quickly re emit far ultraviolet light known as Lyman alpha emission, which is wavelength of 121.6 nanometers. When the first stars formed, some of light they produced matched this wavelength. Because Lyman alpha light easily interacted with hydrogen atoms, it couldn’t travel far before the gas scattered in random directions.

Video Source: NASA
This visualization shows how ultraviolet light from the first stars and galaxies gradually transformed the universe. Hydrogen atoms, also called neutral hydrogen, readily scatters UV light, preventing it from traveling very far from its sources. Gradually, intense UV light from stars and galaxies split apart the hydrogen atoms, creating expanding bubbles of ionized gas. As these bubbles grew and overlapped, the cosmic fog lifted. Astronomers call this process reionization. Here, regions already ionized are blue and translucent, areas undergoing ionization are red and white, and regions of neutral gas are dark and opaque. Credits: M. Alvarez, R. Kaehler and T. Abel (2009)

The Intense light from galaxies can ionize the surrounding hydrogen gas, forming bubbles that allow starlight to travel freely,” said by the team member Vithal Tilvi, a researcher at the Arizona State University in Tempe. “EGS77 formed a large bubble that allows its light to travel to Earth without much attenuation. Eventually, bubble like these grew around all the galaxies and filled intergalactic space, reionizing the universe and clearing the way for light to travel across the cosmos.”
This illustration of the EGS77 galaxy group
Credits: NASA, ESA and V. Tilvi (ASU)
EGS77 discovered as part of the Cosmic Deep And Wide Narrowband (Cosmic DAWN) survey, for which Rhoads serves as principal investigator. The team is imaged a small area in the constellation Bo├Âtes using a custom built filter on the National Optical Astronomy Observatory’s Extremely Wide Field InfraRed Imager (NEWFIRM), which was attached to the four-meter Mayall telescope at Kitt Peak National Observatory near Tucson, Arizona.

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