Distant galaxy discovered from Hubble images

Scientists have spotted an edge- on disk galaxy studded with brilliant patches of newly formed stars, by using a new analysis to obtain sharper images of the distant universe captured by NASA's Hubble Space Telescope.

By applying the analysis to a galaxy magnified by a gravitational lens, astronomers obtained images ten times sharper than what Hubble could achieve on its own.

"When we saw the reconstructed image we said, 'Wow, it looks like fireworks are going off everywhere,'" said astronomer Jane Rigby of NASA's Goddard Space Flight Center in Greenbelt, Md.

The galaxy in question is so far away that we see it as it appeared 11 billion years ago, only 2.7 billion years after the Big Bang.

It is one of more than 70 strongly lensed galaxies studied by the Hubble Space Telescope, following up targets selected by the Sloan Giant Arcs Survey, which discovered hundreds of strongly lensed galaxies by searching Sloan Digital Sky Survey imaging data covering one-fourth of the sky.

"Mining the Sloan Digital Sky Survey has given us the opportunity to peer inside a distant star-forming galaxy with a sharpness of vision never before allowed," said Michael Gladders, associate professor at University of Chicago in the US.

"Admittedly, it's a highly distorted view - like looking at your reflection in the famous Chicago 'Bean' - but with some work we can and have reconstructed a detailed image of the distant galaxy," said Gladders.

The galaxy cluster shown here was discovered as part of the Sloan Giant Arcs Survey. It is located about six billion light-years from Earth and contains hundreds of galaxies.

Researchers had been grappling with the gravity of a giant cluster of galaxies between the target galaxy and Earth that distorts the more distant galaxy's light, stretching it into an arc and also magnifying it almost 30 times.

The team had to develop special computer code to remove the distortions caused by the gravitational lens, and reveal the distant galaxy as it would normally appear.
The resulting reconstructed image revealed two dozen clumps of newborn stars, each spanning about 200 to 300 light-years.

This contradicted theories suggesting that star-forming regions in the distant, early universe were much larger: 3,000 light-years or more in size.

"There are star-forming knots as far down in size as we can see," said doctoral student Traci Johnson of the University of Michigan in the US.

Without the magnification boost of the gravitational lens, the disk galaxy would appear perfectly smooth and unremarkable to Hubble. This would give astronomers a very different picture of where stars are forming.

While Hubble highlighted new stars within the lensed galaxy, NASA's James Webb Space Telescope will uncover older, redder stars that formed even earlier in the galaxy's history.

It will also peer through any obscuring dust within the galaxy.

The findings appear in The Astrophysical Journal Letters.