Looking Back

Given the immense size of our universe, astronomers often speak about looking back in time: the light reaching a telescope from a star one million light-years away takes one million years to reach Earth, so that star will appear to the astronomer's eye as it did one million years ago. Today, astronomers from the University of Massachusetts (UMass) Amherst and Mexico's Instituto Nacional de Astrofísica, Óptica y Electrónica announced that they used a new telescope to crane their eyes almost as far back in time as we've ever looked: 12.8 billion years ago, to a dusty galaxy created in the honeymoon glow following the Big Bang.

"The Big Bang happened 13.7 billion years ago, and now we are seeing this galaxy from 12.8 billion years ago, so it was forming within the first billion years after the Big Bang," said Min Yun, a UMass Amherst astrophysicist and one of the foremost experts in collecting data about distant cosmic objects, in a press release.

The Large Millimeter Telescope. Image Credit: UMass Amherst

Yun's team spotted the distant object using the Large Millimeter Telescope (LMT), located on the summit of Mexico's Sierra Negra, a 15,000-foot extinct volcano. When it becomes fully operational this winter, the LMT will be the most sensitive instrument of its kind in the world.

Astrophysicists believe that the universe was too hot and too uniform to create anything at all for its first 400 million years of existence, and that the first stars and galaxies only began forming between 500 million and a billion years in. Therefore, says Yun, "This new object is very close to being one of the first galaxies ever to form."

Eye on the Sky

This distant galaxy was first detected by NASA"s Herschel Space Telescope, a space-based infrared telescope that was retired in 2013. The galaxy was so distant that the telescope only yielded a blurry image, so astronomers passed the project onto the team at the LMT. Jorge Zavala, a graduate student at the LMT at the time, is the first author of a new paper on the discovery, published in Nature Astronomy.

Zavala and Yun's team was able to measure the object's distance by measuring its redshift, or the degree to which light has shifted towards the red end of the spectrum. This shift is caused by the expansion of the universe, and can be used to determine how fast the object is receding from the observer — and thus, how far away it is.

"These high redshift, very distant objects are a class of mythical beasts in astrophysics," Yun said in the press release. "We always knew there were some out there that are enormously large and bright, but they are invisible in visible light spectrum because they are so obscured by the thick dust clouds that surround their young stars."

The higher resolution and sensitivity promised by the LMT, once it is fully operational, promises that we will be able to find even fainter and more distant objects and phenomena. Astronomers like Yun are unsurprisingly excited about the telescope's potential.

"Now, it could be that there are a whole bunch of them out there and we haven't been able to see them, but with the LMT we have the power to see them," Yun said. "I'm always hoping that these things will pop out. You have to be a hopeless optimist to be doing this kind of work, and this time it absolutely paid off."

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