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Hubble uses gravitational lens to look back at the early universe

The Hubble Space Telescope is the most capable astronomical instrument humanity has ever deployed. Over its quarter century of operation, it has made huge contributions to our understanding of the universe. Still, Hubble was designed decades ago, and it can’t do everything astronomers might like it to. Sometimes it needs a little help from the cosmos itself to see what’s out there. That’s the goal of the Frontier Fields project, which is how Hubble captured this new image, one of the deepest views into space ever.

The field of galaxies in the center of the image above is known as Abell S1063, which is about 4 billion light years away. That’s quite distant, but it’s far from the most distant thing Hubble has ever observed. The target of the Frontier Fields project isn’t actually the galaxy cluster, but what’s behind it. The objects behind Abell S1063 are what astronomers are truly interested in. Those galaxies are from the very early universe, just a billion or so years after the big bang.

This extra long-distance view is possible because of a phenomenon called gravitational lensing. Objects with sufficient gravity can warp the universe and redirect light — this is a consequence of general relativity. This creates a natural lens, through which Hubble can look to get a clearer view of objects on the other side. That’s the focus of the Frontier Fields project, which has already peered through three other gravitational lenses in other galaxy clusters, with two more on the agenda.

Researchers are still analyzing the data gathered from Abell S1063, but already they’ve spotted one galaxy that formed a billion years after the Big Bang. This is key in understanding what the early universe looked like. Researchers have also identified 16 galaxies in the image that have been distorted by the lens, causing two or three copies of them to show up. This can help astronomers develop models of the distribution of dark matter and regular matter in the lensing cluster (it’s this gravity that’s causing the distortion, after all).

The use of gravitational lenses is a good way to extend the usefulness of Hubble in its twilight years. As the universe expands, it stretches the light from very distant objects past the longest near-infrared wavelengths Hubble is capable of detecting. A gravitational lens brings them back into focus, but the upcoming James Webb Space Telescope won’t need gravitational lenses to view many of these objects. Currently on schedule for a late 2018 launch, the Webb telescope can observe wavelengths of light up to 10 times longer than Hubble. Then maybe we’ll get to the bottom of this whole “nature of the universe” thing once and for all.

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