Thanks to the presence of a natural “zoom lens” in space, NASA’s Hubble Space Telescope got a uniquely close-up look at the brightest “magnified” galaxy yet discovered. In this image the light from a distant galaxy, nearly 10 billion light-years away, has been warped into a nearly 90-degree arc of light in the galaxy cluster RCS2 032727-132623.
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The galaxy cluster lies 5 billion light-years away. So-called gravitational lens is produced when space is warped by a massive foreground object, whether it is the sun, a black hole or an entire cluster of galaxies. The light from more-distant background objects is distorted, brightened and magnified as it passes through this gravitationally disturbed region. The presence of the lens helps show how galaxies evolved from 10 billion years ago to today. While nearby galaxies are fully mature and are at the tail end of their star-formation histories, distant galaxies tell us about the universe’s formative years. The light from those early events is just now arriving at Earth. Very distant galaxies are not only faint but also appear small on the sky. Astronomers would like to see how star formation progressed deep within these galaxies. Such details would be beyond the reach of Hubble’s vision were it not for the magnification made possible by gravity in the intervening lens region. 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 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. Through spectroscopy, the spreading out of the 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.