“We find them smaller and fainter, in constantly increasing numbers, and we know that we are reaching into space, farther and farther, until, with the faintest nebulae that can be detected with the greatest telescopes, we arrive at the frontier of the known universe.” -Edwin Hubble
When you look out at the distant Universe, you can see all sorts of things: stars, galaxies, clusters of galaxies, going as far back into the distant past as our telescopes can image. But where you have the greatest concentrations of mass, an extreme phenomenon emerges: that of gravitational lensing. Any foreground objects lying behind that mass will have their light stretched, magnified and distorted by the intervening matter.
An illustration of gravitational lensing showcases how background galaxies — or any light path — is distorted by the presence of an intervening mass, such as a foreground galaxy cluster. Image credit: NASA / ESA.
Recently, as part of the Hubble Frontier Fields program, the telescope followed-up on galaxy cluster Abell 370, and revealed the most spectacular gravitational lensing signal ever seen in a galaxy cluster. Most importantly, it provides some very strong evidence not only for dark matter’s existence, but for its presence distinct from any galaxies at all.
Despite the presence of large, elliptical galaxies, the location where the mass density is greatest, indicated by the dotted circle, corresponds to no known massive galaxy or other structure based in normal matter. The only explanation for this is the presence of an invisible source of mass: dark matter. Image credit: NASA, ESA/Hubble, HST Frontier Fields / E. Siegel (annotation).
from ScienceBlogs http://ift.tt/2qSsZrv
“We find them smaller and fainter, in constantly increasing numbers, and we know that we are reaching into space, farther and farther, until, with the faintest nebulae that can be detected with the greatest telescopes, we arrive at the frontier of the known universe.” -Edwin Hubble
When you look out at the distant Universe, you can see all sorts of things: stars, galaxies, clusters of galaxies, going as far back into the distant past as our telescopes can image. But where you have the greatest concentrations of mass, an extreme phenomenon emerges: that of gravitational lensing. Any foreground objects lying behind that mass will have their light stretched, magnified and distorted by the intervening matter.
An illustration of gravitational lensing showcases how background galaxies — or any light path — is distorted by the presence of an intervening mass, such as a foreground galaxy cluster. Image credit: NASA / ESA.
Recently, as part of the Hubble Frontier Fields program, the telescope followed-up on galaxy cluster Abell 370, and revealed the most spectacular gravitational lensing signal ever seen in a galaxy cluster. Most importantly, it provides some very strong evidence not only for dark matter’s existence, but for its presence distinct from any galaxies at all.
Despite the presence of large, elliptical galaxies, the location where the mass density is greatest, indicated by the dotted circle, corresponds to no known massive galaxy or other structure based in normal matter. The only explanation for this is the presence of an invisible source of mass: dark matter. Image credit: NASA, ESA/Hubble, HST Frontier Fields / E. Siegel (annotation).
from ScienceBlogs http://ift.tt/2qSsZrv
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