Thanks to the presence of a natural “zoom lens” in space, University of Chicago scientists working with NASA’s Hubble Space Telescope have obtained a uniquely close-up look at the brightest gravitationally magnified galaxy yet discovered.
The imagery offers a visually striking example of gravitational lensing, in which one massive object’s gravitational field can magnify and distort the light coming from another object behind it. Such optical tricks stem from Einstein’s theory of general relativity, which describes how gravity can warp space and time, including bending the path that light travels.
In this case, gravity from the galaxy cluster RCS2 032727-132623 bent and amplified the light coming from a much more distant galaxy, 10 billion light-years from Earth. This “gravitational telescope” creates a vast arc of light, as if the distant galaxy had been reflected in a funhouse mirror. The UChicago team reconstructed what the distant galaxy really looks like, using computational tools that reversed the effect of gravitational lensing.
“What’s happening here is a manifestation of general relativity,” said Michael Gladders, assistant professor in astronomy & astrophysics at UChicago. “Instead of seeing the normal, faint image of that distant source, you see highly distorted, highly magnified, and in this case, multiple images of the source caused by the intervening gravitational mass.”
The cosmic lens gave the UChicago team the unusual opportunity to see what a galaxy looked like 10 billion years ago. The reconstructed image of the galaxy revealed regions of star formation glowing like bright points of light. These are much brighter than any star-formation region in Earth’s home galaxy, the Milky Way.
'Looking at the nature of dark matter'
In 2006 the Chicago astronomers used the Very Large Telescope in Chile to measure the arc’s distance and calculated that the galaxy appears more than three times brighter than previously discovered lensed galaxies. Then last year, Jane Rigby of NASA’s Goddard Space Flight Center in Greenbelt, Md., and the Chicago team imaged the arc with the Hubble Space Telescope’s Wide Field Camera 3.