How the Hubble Telescope found a galaxy 13.1 billion light years away

The Hubble Space Telescope, which helped identify the farthest known galaxy in the universe, offers insight into how other old galaxies formed.
By Sam Klein | May 07, 2015
The universe is extremely old we were reminded of this fact again this week when scientists at Yale and the University of California Santa Cruz discovered a galaxy that is believed to be 13.1 billion years old dating almost back to the Big Bang. EGS-zs8-1, the ancient galaxy, has had the astronomy community jumping with joy, but it certainly not the only galaxy dating back to the dawn of the universe. In fact, the Hubble Telescope has been doing the work that led to this discovery for years. The giant telescope has been collecting data on other galaxies for years, and it is now allowing us to fill in the gaps in the universe's long history.

The Hubble Telescope captures data about the universe 24 hours a day, 365 days a year. It coverts digital signals into images, and requires considerable effort from researchers to produce something like a picture of an ancient galaxy. Each year scientists from all over the world compete for time with the massive telescope, hoping to use its unrivaled view of the universe to answer their burning scientific questions.

The Hubble is constantly locating galaxies that we didn't previously know about. In October 2014, Hubble researchers found a galaxy behind the cluster Abell 2744, also known as Pandora's Cluster. The galaxy is also estimated to be slightly over 13 billion years old. Pandora's Cluster is so large that its gravitational force bends the light from the galaxies far behind it. This phenomenon, called "gravitational lensing," makes objects behind the cluster appear larger and brighter.

Images from the Hubble also tell us about the history of our own galaxy, the Milky Way. The stellar "baby boom" that formed the Milky Way about 10 billion years ago occurred long before the birth of our own sun. Scientists were able to extrapolate the timeline for the formation of our own galaxy by comparing it to many other galaxies with a similar mass. The census gathered by the Hubble Telescope consists of over 2000 snapshots of other ancient galaxies.

The galaxy discovered this week lies in the constellation Botes,and is located 13.1 billion light years from earth. There are two theories that describe how a galaxy is formed. One posits that galaxies form when vast clouds of dust and gas collapse under their own gravitational force, allowing them to coalesce into stars. The other theory says that the nascent universe contained many small clumps of matter, which gravitated together to form galaxies. The Hubble telescope has photographed many of these lumps, and the second theory is gaining acceptance within the astronomy community.

Since the speed of light limits how fast energy from a distant galaxy can reach the Hubble's lens, we can calculate that it took 13.1 billion years for the light from EGS-zs8-1 to arrive on Earth. When we look at the image of the ancient galaxy, we are quite literally looking back in time. It's entirely possible that the stars in this galaxy look like something entirely different today; we wouldn't know about it until the light coming from the galaxy today reaches the earth, 13.1 billion years from now.

According to research from Yale, age and distance are crucially connected when considering the scale of the universe. The light that we rely on from the sun takes a full eight minutes to reach us from the center of our own solar system, while the light from distant galaxies must travel for billions of years before advanced telescopes are able to detect it. We look into the past when we observe this light.

The previous oldest know galaxy was about 30 million years younger than EGS-zs8-1. UC Santa Cruz astronomer Garth Illingworth, who co-authored the paper inAstrophysical Journal Letters,said that the difference wasn't much at all when dealing with distances this great, but it was difficult to reach the conclusion.

The new observations about the galaxy offer important insight into the early universe. Based on the discovery, astronomers have been able to determine that at the time ESG-zs8-1 was forming, the hydrogen found between galaxies was transforming from a neutral to an ionized state. The study's co-author, Rychard Bouwens of the Leiden Observatory, said that the early galaxies like EGS-zs8-1 were the primary drivers of this chemical change.

The photos of the new galaxy also raise new questions. They confirm the hypothesis that large galaxies existed very early in the universe, and they also show how different their physical properties were to our Milky Way today. The odd colors found in early galaxies, according to astronomers, originate from the gases involved in the rapid formation of large, young stars.

Though nobody can deny the contributions to our understanding of the universe made by the Hubble Telescope, researchers at UC Santa Cruz reported that they think it will be easy to accurately measure the distances to far-away galaxies like ESG-zs8-1 in the near future using the super-powerful James Webb Space Telescope, to be launched in 2018. The measurements that will be provided by the telescope are hoped to provide a more complete picture of the early universe.



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