Universe's Most Distant Object Spotted

Astronomers spotted a faint glimmer of infrared light from this primitive galaxy, called UDFy-38135539, using the European Southern Observatory's Very Large Telescope in Chile.

Because of the time it takes for the distant galaxy's light to reach Earth, the recently captured signal is thought to have been emitted when the universe was only 600 million years old. That means the find can help scientists better understand the so-called era of reionization, the study authors say.

For about the first billion years after the big bang, the universe was filled with an opaque fog of neutral hydrogen. As the very first stars and galaxies formed out of this fog, their radiation charged any nearby hydrogen. This ionization transformed the fog into the optically transparent interstellar medium that exists today.

(Related: "Big Bang Ripples Formed Universe's First Stars.")

"The universe at the time was quite an interesting place, as progressively more and more galaxies were formed, while the existing galaxies were merging together and growing in size and luminosity," said Michele Trenti, a postdoctoral research associate at the University of Colorado in Boulder who was not involved in the study.

"The photons emitted from these galaxies were stripping off electrons from the hydrogen atoms in the interstellar gas, creating bubbles of ionized gas surrounding these [galaxies].

"This bubble"—the one surrounding the newfound galaxy—"is proof that after about 600 million years from the big bang, stars in galaxies have almost completed the process of hydrogen reionization."


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