Mystery solved! Bizarre Hubble double galaxy caused by 'ripple' in space
By Rahul Rao about 5 hours ago
Dark matter is involved.
This Hubble Space Telescope snapshot shows three magnified images of a distant galaxy embedded in a cluster of galaxies. These images are produced by a trick of nature called gravitational lensing. The galaxy cluster's immense gravity magnifies and distorts the light from the distant galaxy behind it, creating the multiple images. Two of the magnified images, shown in the pull-out at bottom right, are exact copies of each other. The two bright ovals are the cores of the galaxy. This rare phenomenon occurs because the background galaxy straddles a ripple in the fabric of space. This “ripple” is an area of greatest magnification, caused by the gravity of dense amounts of dark matter. (Image credit: Joseph DePasquale (STScI))
Astronomers believe they’ve solved, at long last, a mystery first discovered nearly a decade ago by the Hubble Space Telescope.
The dilemma centered on a strange "double galaxy," a pair of streaky objects that once defied explanation. Now, scientists think, the objects are actually one distant galaxy that appears as two thanks to a "ripple" in the fabric of space that is magnifying and distorting its image.
From Earth, the doubled objects almost 11 billion light-years away look like mirror images of each other. When astronomers first saw them in 2013, they immediately suspected a case of gravitational lensing — a phenomenon that occurs when light from a faraway object is warped, like an image through a fishbowl, by the gravity of something else between that object and the observer.
That answered the how, but not the what or why. Hubble has glimpsed quite a few gravitationally lensed objects in its time, and this one was more than a mere warp. Gravitational lensing was somehow not just magnifying the galaxy but also copying it, creating two bright images, as well as a fainter third copy that can also be seen in the image.
More:
https://www.space.com/hubble-telescope-double-galaxy-dark-matter-ripple-photo?utm_source=notification
