Hubble Captures The Same Galaxy Gravitationally Lensed 12 Times

This NASA/ESA Hubble Space Telescope image shows a massive galaxy cluster and around it the gravitationally lensed images of a galaxy, nicknamed the Sunburst Arc. ESA/Hubble, NASA, Rivera-Thorsen et al.

The Romans used to say “repetita iuvant”, which means "repeated things help". And Hubble will certainly have plenty of help studying the Sunburst Arc galaxy as its image is repeated a whopping 12 times across the night sky.

The galaxy is subjected to a phenomenon known as gravitational lensing. If you have a massive foreground object it can act as a lens by warping space-time around it. Light from background galaxies is thus magnified, stretched, and in cases such as this, multiplied.

The Hubble Space Telescope has identified at least 12 images of the Sunburst Arc, a galaxy that is located slightly less than 11 billion light-years away. Its light is being lensed by a large cluster of galaxies 4.6 billion light-years from us. In some parts, the galaxy is magnified 10 to 30 times, allowing Hubble to resolve areas as small as 520 light-years across.

This is a big area in human terms, but space-wise, it's actually quite small. Seeing it from such a distance with a space telescope such as Hubble is very impressive. This level of detail allows astronomers to compare this galaxy to nearby objects, and use it as a proxy for the very first galaxies in the universe.

These first galaxies formed a lot of bright stars very quickly and these stars produced intense ultraviolet rays that ripped the electrons off hydrogen atoms not just in the galaxy, but also in intergalactic space. It is unclear exactly how this process took place as the ultraviolet photons should have been absorbed by interstellar matter. These new observations of the Sunburst Arc galaxy provide an important piece of the puzzle.

As reported in Science, ultraviolet light escapes the Sunburst Arc through narrow channels that penetrate the rich neutral hydrogen medium that surrounds the galaxy. This is a process that has been considered for a long time and these observations confirm that it actually happens.  

The Sunburst Arc galaxy doesn’t belong to the same family as the first galaxy but what goes on there provides important insights into how galaxies ionize their surroundings. The process seen in this study might not be the main way for UV light to escape but it could have played an important role in the early universe.

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