The Most Distant Galaxy in the Observable Universe Discovered --30 Billion Light Years from the Milky Way!
The image above from the Hubble Space Telescope CANDELS survey, highlights the most distant galaxy in the universe with a measured distance, dubbed z8_GND_5296. The most distant spectroscopically confirmed galaxy ever found — one created at about 700 million years after the Big Bang — has been detected by astronomers at Texas A&M University and the University of Texas at Austin.
The astronomers note that this is one of two major changes in the fundamental essence of the universe since its beginning — the other being a transition from a plasma state to a neutral state. He is leading the effort on a follow-up paper that will use a sophisticated statistical analysis to explore that transition further.
“Everything seems to have changed since then,” said Vithal Tilvi, a Texas A&M postdoctoral research associate and co-author of the paper now available online.“If it was neutral everywhere today, the night sky that we see wouldn’t be as beautiful. What I’m working on is studying exactly why and exactly where this happened. Was this transition sudden, or was it gradual?”
Our home galaxy, the Milky Way, creates about one or two Sun-like stars every year or so. But this newly discovered galaxy forms around 300 a year. It was observed by the researchers as it was 13 billion years ago. Because the universe has been expanding the whole time, the researchers estimate the galaxy’s present distance to be roughly 30 billion light years away. The detected emission line at a wavelength of 1.0343 micrometres is likely to be Lyman α emission, placing this galaxy at a redshift z = 7.51, an epoch 700 million years after the Big Bang.
The galaxy’s colors are consistent with significant metal content, implying that galaxies become enriched rapidly. The astronomers calculated a surprisingly high star-formation rate of about 330 solar masses per year, which is more than a factor of 100 greater than that seen in the Milky Way. Such a galaxy is unexpected in a survey of our size, suggesting that the early Universe may harbour a larger number of intense sites of star formation than expected.
“Because of its distance we get a glimpse of conditions when the universe was only about 700 million years old — only 5 percent of its current age of 13.8 billion years,” said Texas A&M astrophysicist Casey Papovich, an associate professor in the Department of Physics and Astronomy and a member of the George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy.
The Nature paper is the result of raw data gleaned from a powerful Hubble Space Telescope imaging survey of the distant universe called CANDELS, or Cosmic Assembly Near-Infrared Deep Extragalactic Legacy Survey. Using that data, the team was armed with 43 potential distant galaxies and set out to confirm their distances.
Because the universe is expanding, the space between galaxies also is increasing. And as objects move away, they become redder. In essence, the higher the redshift, the farther away the object. Only five other galaxies have ever been confirmed to have a redshift greater than 7, with the previous high being 7.215.
Papovich notes that researchers are also able to accurately gauge the distances of galaxies by measuring a feature from the ubiquitous element hydrogen called the Lyman alpha transition, which emits brightly in distant galaxies. It’s detected in nearly all galaxies that are seen from a time more than one billion years from the Big Bang, but getting closer than that, the hydrogen emission line, for some reason, becomes increasingly difficult to see.
“We were thrilled to see this galaxy,” said the Nature paper’s lead author, Steven Finkelstein, an assistant professor at the University of Texas at Austin and 2011 Hubble Fellow. “And then our next thought was, ‘Why did we not see anything else? We’re using the best instrument on the best telescope with the best galaxy sample. We had the best weather — it was gorgeous. And still, we only saw this emission line from one of our sample of 43 observed galaxies, when we expected to see around six. What’s going on?’”
Finkelstein credits technological advancements in recent years for allowing astronomers to probe deeper into space and closer to the Big Bang. For instance, a powerful new spectrometer called MOSFIRE (Multi-Object Spectrometer For Infra-Red Exploration) that is 25 times more light-sensitive than others of its kind was installed at Keck in 2012. And the Hubble Space Telescope is powered by a new near-infrared camera installed by astronauts aboard the Space Shuttle in 2009 that sees farther into the universe.
“It’s exciting to know we’re the first people in the world to see this,” said Tilvi, “It raises interesting questions about the origins and the evolution of the universe.”
Ten other international institutions collaborated on the effort, from California to Massachusetts and Italy to Israel.
The Daily Galaxy via the Hubble Space Telescope Science Institute (STScI), and Texas A&M astronomy http://astronomy.tamu.edu/.
Image credit: V. Tilvi, Texas A&M University; S.L. Finkelstein, University of Texas at Austin; C. Papovich, Texas A&M University; CANDELS Team and Hubble Space Telescope/NASA.