NASA Uses Ancient Galaxy Like a Magnifying Glass
Astronomers have found the oldest known galaxy to date -- that can be used as an interstellar magnifying glass to detect other, more distant galaxies.
Using the National Aeronautics and Space Administration's Hubble Space Telescope, researchers discovered a galaxy that weighs an estimated 180 billion times more than our sun and, at least when it generated the light we see now about 9.6 billion years ago, was comparatively a massive galaxy.
Beating out the previous oldest lens galaxy by 200 million years, the new galaxy is one of the brightest members of a distant cluster of galaxies known as IRC 0218, according to a NASA news release.
Such galaxies are so big that their gravity bends, magnifies, and distorts light originating from objects behind it, a phenomenon called gravitational lensing.
The object seen behind the cosmic lens galaxy in question is a tiny spiral galaxy, the light of which took about 10.7 billion years to reach Earth.
When that light was emitted, the observed galaxy was undergoing a rapid burst of star formation.
"When you look more than 9 billion years ago in the early universe, you don't expect to find this type of galaxy lensing at all," lead researcher Kim-Vy Tran of Texas A&M University in College Station said in the release. "It's very difficult to see an alignment between two galaxies in the early universe. Imagine holding a magnifying glass close to you and then moving it much farther away. When you look through a magnifying glass held at arm's length, the chances that you will see an enlarged object are high. But if you move the magnifying glass across the room, your chances of seeing the magnifying glass nearly perfectly aligned with another object beyond it diminishes."
Fellow researchers Kenneth Wong and Sherry Suyu of Academia Sinica Institute of Astronomy & Astrophysics in Taiwan used the gravitational lensing that resulted from the alignment of the two galaxies to measure the giant galaxy's total mass, including the amount of dark matter.
Dark matter cannot be seen, but accounts for the majority of the universe's matter.
Locating more distant lensing galaxies will offer greater understanding of how young galaxies in the early universe built themselves up into the massive dark-matter-dominated galaxies of today.
"There are hundreds of lens galaxies that we know about, but almost all of them are relatively nearby, in cosmic terms," said Wong, first author on the team's science paper. "To find a lens as far away as this one is a very special discovery because we can learn about the dark-matter content of galaxies in the distant past. By comparing our analysis of this lens galaxy to the more nearby lenses, we can start to understand how that dark-matter content has evolved over time."
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