Discovery of Farthest Known Galaxy Brings New Questions About Early Universe

A faint 13.2 billion-year-old galaxy is the most distant ever observed.

ByALYSSA NEWCOMB
September 7, 2015, 11:24 AM

— -- After the Big Bang created the universe 13.8 billion years ago, scientists believe the first galaxies began to form half a billion to 1 billion years later. Finding such galaxies has been a challenge because their light is so faint, which makes the discovery of a 13.2 billion-year-old galaxy -- the farthest known -- especially intriguing to scientists.

The galaxy, called EGS8p7, was pinpointed as an area for further investigation after scientists evaluated data from the Hubble and Spitzer space telescopes. A team of Caltech researchers then performed a spectrographic analysis of the galaxy, a process used to measure its red shift, which is used to determine the distance a galaxy is from Earth.

In theory, scientists shouldn't have been able to see a galaxy this old because neutral hydrogen atoms were believed to have absorbed radiation from newly formed galaxies, making the older galaxies incredibly faint and virtually undetectable, according to the study published in the Astrophysical Journal Letters.

While scientists aren't certain why they are able to see this galaxy, one theory is that hydrogen reionization during the early beginnings of the universe may have been patchy, explaining why some galaxies are more visible than others.

It's also possible EGS8p7 may be housing hot stars that, in turn, create a giant hydrogen bubble, allowing the galaxy to be seen.

"The galaxy we have observed, EGS8p7, which is unusually luminous, may be powered by a population of unusually hot stars, and it may have special properties that enabled it to create a large bubble of ionized hydrogen much earlier than is possible for more typical galaxies at these times," Sirio Belli, one of the Caltech researchers who worked on the project, said in a statement.

The researchers said they are now taking a closer look at the exact chances of finding this galaxy in order to gain an understanding of whether the timeline of reionization in the early universe needs to be revised.

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