Hubble’s Frontier Fields Looks At Galaxy Cluster Abell 370 Which Is 6 Billion Light-Years Away

Six billion light-years away from Earth is a massive galaxy cluster called Abell 370 whose enormous gravity warps the spacetime around it, causing an effect called gravitational lensing which distorts and magnifies the view of the objects behind it. The galaxy cluster is home to several hundred galaxies that are kept together by the same gravitational pull.

The Hubble Space Telescope — operated jointly by NASA, the European Space Agency (ESA) and the Space Telescope Science Institute (STScI) — captured an image of Abell 370 in unprecedented detail, using 630 hours of observing time over 560 orbits of Earth, according to the telescope’s website. And the resulting image, a combination of visible and near-infrared light photographs, is spectacular in its detail.

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Abell 370 is home to a large variety of galaxy shapes. The yellow-white objects in the image are the largest and brightest galaxies, which are elliptical in shape and contain billions of stars each. The bluish objects are spiral galaxies, like the Milky Way, and are home to younger stars, a statement on NASA’s website said. The arcs of blue that are scattered all over the image are actually remote galaxies behind Abell 370, which are otherwise too faint to be seen by Hubble but are visible in the image due to gravitational lensing.

By studying the lensing properties of this massive galaxy cluster, astronomers also determined it contains two separate, large concentrations of dark matter, which provides evidence for the theory that Abell 370 formed when two smaller clusters merged into one. This sort of analysis contributes to the understanding of the distribution of normal matter and dark matter in the universe.

The Abell 370 image was captured as part of Hubble’s Frontier Fields program, which has produced the deepest observations made yet, of massive galaxy clusters along with the distant, older galaxies that lie behind them. The gravitational lensing effect of the clusters like Abell 370 allow astronomers to get a glimpse of the universe as it existed only a few hundred million years after the Big Bang, or cosmic infancy.

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In the Frontier Fields program, Hubble produced six images of massive galaxy clusters, of which Abell 370 was the last. Along with the clusters, “parallel fields” or regions of space adjacent to the clusters — seemingly sparse — were also imaged with the same exposure that provided a deep look into the early universe. The program has shown galaxies that are 10 to 100 times fainter than any of those previously observed.

Abell 370 was photographed in high resolution as early as the 1980s, and a detailed photograph of it, also taken by Hubble, was released in 2009. The galaxy cluster was one of the very first where the phenomenon of gravitational lensing was observed.