Hubble Zooms in on a Magnified Galaxy
A team of astronomers aimed Hubble at one of the most striking examples of gravitational lensing, a nearly 90° arc of light in the galaxy cluster RCS2 032727-132623. Hubble’s view of the distant background galaxy, which lies nearly 10 billion light-years away, is significantly more detailed than could ever be achieved without the help of the gravitational lens.
The distorted image of the galaxy is repeated several times in the foreground lensing cluster, as is typical of gravitational lenses. The challenge for astronomers was to reconstruct what the galaxy really looked like, were it not distorted by the cluster’s funhouse-mirror effect.
Hubble’s sharp vision allowed astronomers to remove the distortions and reconstruct the galaxy image as it would normally look. The reconstruction (shown at lower left) revealed regions of star formation glowing like bright Christmas tree bulbs. These are much brighter than any star-formation region in our Milky Way galaxy.
The small rectangle in the center shows the location of the background galaxy if the intervening galaxy cluster were not there. The rounded outlines show distinct, distorted images of the background galaxy resulting from lensing by the mass in the cluster.
Through spectroscopy, the spreading out of light into its constituent colors, the team plans to analyze these star-forming regions from the inside out to better understand why they are forming so many stars. This observation provides a unique opportunity to study the physical properties of a galaxy vigorously forming stars when the universe was only one-third its present age.