Academic journal article The Science Teacher

Distant Galaxy Candidate

Academic journal article The Science Teacher

Distant Galaxy Candidate

Article excerpt

Astronomers studying ultra-deep imaging data from the Hubble Space Telescope have found what may be the most distant galaxy ever seen, about 13.2 billion light-years away. The study pushed the limits of Hubble's capabilities, extending its reach back to about 480 million years after the Big Bang, when the universe was just 4% of its current age.

"We're getting back very close to the first galaxies, which we think formed around 200 to 300 million years after the Big Bang," says Garth Illingworth, professor of astronomy and astrophysics at the University of California, Santa Cruz (UCSC).

Illingworth and former UCSC astronomer Rychard Bouwens-now at Leiden University in the Netherlands-led the study, published in the journal Nature. Using infrared data gathered by Hubble's Wide Field Planetary Camera 3 (WFC3), they were able to see dramatic changes in galaxies over a period about 480 to 650 million years after the Big Bang. The rate of star birth in the universe increased by 10 times during this 170-million-year period, Illingworth says.

"This is an astonishing increase in such a short period, just 1% of the current age of the universe," he says. There were also striking changes in the numbers of galaxies detected.

"Our previous searches had found 47 galaxies at somewhat later times, when the universe was about 650 million years old. However, we could only find one galaxy candidate just 170 million years earlier," Illingworth says. "The universe was changing very quickly in a short amount of time."

According to Bouwens, these findings are consistent with the hierarchical picture of galaxy formation, in which galaxies grew and merged under the gravitational influence of dark matter. "We see a very rapid build up of galaxies around this time," he says. "For the first time now, we can make realistic statements about how the galaxy population changed during this period and provide meaningful constraints for models of galaxy formation. …

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