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Most Distant Gravitational LensLight is affected by gravity. When light passes by a massive object, its path will be deflected. When the source of the light is a distant galaxy, and the massive object it encounters (another galaxy, for instance) lies between the observer and the light source, we have what is known as a gravitational lens. When the observer, the lens and the light source are precisely aligned, a sort of natural telescope is created. The observer sees an Einstein ring: a circle of light that is the projected and greatly magnified image of the distant light source, allowing astronomers a more detailed look at distant galaxies than is normally possible.Albert Einsteins’s general theory of relativity predicted the existence of gravitational lenses, and the first example of one was discovered in 1979. Since then, astronomers have found more, and now, an international team has found the most distant example yet. The lensing mass is at an estimated distance of 9.4 billion light-years, or nearly twenty percent more distant than the previous record holder.The discovery came completely by chance. Lead author Arjen van der Wel of the Max Planck Institute for Astronomy in Heidelberg, Germany was reviewing observations from an earlier project when he spotted an anomaly: a very young galaxy at a larger distance than expected. Intrigued, he studied images taken by the Hubble Space Telescope as part of the CANDELS and COSMOS surveys. In these images, the target looked like an old galaxy, albeit one with some irregular features. He began to suspect he was looking at a gravitational lens. When he combined all the images and removed the haze of the lensing galaxy’s stars, an almost perfect Einstein ring emerged. The team had found a very precisely aligned gravitational lens, and at a record distance to boot.Aside from magnifying the source object, gravitational lenses provide another valuable benefit to scientists. The amount of distortion caused by the lensing galaxy allows for a direct measurement of its total mass, including any dark matter that might be present. Nice of nature to provide a multi-tool for astronomers!Of course, nature can also throw a wrench in the works. In this case, the magnified object is a starbursting dwarf galaxy. These are light galaxies (one thousand times less mass in the form of stars than the Milky Way) that are very young (only 10-40 million years old) and are producing new stars at a prodigious pace. That makes these galaxies fairly peculiar and somewhat rare. So what are the chances of gravitationally lensing such a galaxy? Vey small, indeed. And yet this is the second starbursting dwarf galaxy to be lensed. Either astronomers are a very lucky lot, or the peculiar galaxies are much more common than current theories of galaxy evolution predict.Van der Wel concludes: “This has been a weird and interesting discovery. It was a completely serendipitous find, but it has the potential to start a new chapter in our description of galaxy evolution in the early Universe.” -JFImage credit: NASA/ESA/A. van der WelSourceFor more from Hubble and the ESA:https://www.facebook.com/hubbleESAhttp://spacetelescope.org/ View high resolution

Most Distant Gravitational Lens

Light is affected by gravity. When light passes by a massive object, its path will be deflected. When the source of the light is a distant galaxy, and the massive object it encounters (another galaxy, for instance) lies between the observer and the light source, we have what is known as a gravitational lens. When the observer, the lens and the light source are precisely aligned, a sort of natural telescope is created. The observer sees an Einstein ring: a circle of light that is the projected and greatly magnified image of the distant light source, allowing astronomers a more detailed look at distant galaxies than is normally possible.

Albert Einsteins’s general theory of relativity predicted the existence of gravitational lenses, and the first example of one was discovered in 1979. Since then, astronomers have found more, and now, an international team has found the most distant example yet. The lensing mass is at an estimated distance of 9.4 billion light-years, or nearly twenty percent more distant than the previous record holder.

The discovery came completely by chance. Lead author Arjen van der Wel of the Max Planck Institute for Astronomy in Heidelberg, Germany was reviewing observations from an earlier project when he spotted an anomaly: a very young galaxy at a larger distance than expected. Intrigued, he studied images taken by the Hubble Space Telescope as part of the CANDELS and COSMOS surveys. In these images, the target looked like an old galaxy, albeit one with some irregular features. He began to suspect he was looking at a gravitational lens. When he combined all the images and removed the haze of the lensing galaxy’s stars, an almost perfect Einstein ring emerged. The team had found a very precisely aligned gravitational lens, and at a record distance to boot.

Aside from magnifying the source object, gravitational lenses provide another valuable benefit to scientists. The amount of distortion caused by the lensing galaxy allows for a direct measurement of its total mass, including any dark matter that might be present. Nice of nature to provide a multi-tool for astronomers!

Of course, nature can also throw a wrench in the works. In this case, the magnified object is a starbursting dwarf galaxy. These are light galaxies (one thousand times less mass in the form of stars than the Milky Way) that are very young (only 10-40 million years old) and are producing new stars at a prodigious pace. That makes these galaxies fairly peculiar and somewhat rare. So what are the chances of gravitationally lensing such a galaxy? Vey small, indeed. And yet this is the second starbursting dwarf galaxy to be lensed. Either astronomers are a very lucky lot, or the peculiar galaxies are much more common than current theories of galaxy evolution predict.

Van der Wel concludes: “This has been a weird and interesting discovery. It was a completely serendipitous find, but it has the potential to start a new chapter in our description of galaxy evolution in the early Universe.” 

-JF

Image credit: NASA/ESA/A. van der Wel

Source

For more from Hubble and the ESA:
https://www.facebook.com/hubbleESA
http://spacetelescope.org/

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