Oldest galaxy provides Big Bang insights

Astronomers from the University of California, Riverside, working in collaboration with the University of Texas at Austin, the National Optical Astronomy Observatories, and other institutions nationwide have discovered what they believe to the be farthest known galaxy to date.

First seen with the Hubble Space Telescope, the distant galaxy, designated as Z8-GND-5296, has been observed as it was just 700 million years after the big bang, an estimated 30 billion light years away.

Researchers working on the project discovered the galaxy after searching through a database of nearly 100,000 galaxies imaged by the Hubble Space Telescope as part of the CANDELS survey. Deep optical and infrared images taken by this survey allowed astronomers to pinpoint several remote galaxies whose distances were then confirmed by MOSFIRE, a new high powered spectrometer commissioned in 2012.

This extremely sensitive instrument, located at the Kerk observatory in Hawaii, is able to detect infrared light and allows researchers to measure a phenomenon known as “red shift”- the shifting of wavelength towards the infrared end of the light spectrum when objects move away from one another. Red shift is essentially the visual counterpart to the Doppler Effect. Because the velocity at which the object are moving apart and distance they are from one another is proportional, red shift can be used to measure the distance of galaxies in relation to Earth.

With the aid of MOSFIRE, the team analyzed 43 different galaxies using the Lyman alpha transition of the element hydrogen and the extent of redshift displayed by each. Of these 43 galaxies, only Z8-GND-5296 displayed the Lyman alpha transition. It also exhibited a redshift of 7.6, the highest ever recorded.

From the data collected, researchers estimate that Z8-GND-5296 is roughly 30 billion light years from earth and continuing to move further away as the universe expands.  Since light observed from the distant galaxy reached Earth 30.1 billion years after it was emitted, researchers are able to view the galaxy as it was only 700 million years after the big bang. This is extremely important, researchers say, as studying galaxies such as this can lead to a better understanding of the early formation and evolution of the universe. In addition to its extraordinary distance from Earth, Z8-GND-5296 also has an incredibly fast production of stars- up to 150 times that of the Milky Way.

Even more striking to researchers is that although they expected to observe the Lyman alpha transition in as many as 6 of the 43 galaxies that they analyzed it was seen in only one. They believe that they may have detected what is known as the Era of Re-ionization. During this period of time the early universe shifted from an opaque state containing mostly neutral hydrogen to a more translucent state in which most hydrogen is ionized. Thus, the emissions from distant galaxies in this era would be shielded. More distant and ancient galaxies may exist in this haze but their detection, at least for now, is beyond reach. Only further research and advances in technology will allow researchers to peer further into the universe’s most ancient and distant depths and truly reveal the secrets behind its formation.