Kicking in the Void

NASA, ESA, CFHT, CXO, M.J. Jee (Uni­ver­sity of Cal­i­for­nia, Davis), and A. Mah­davi (San Fran­cisco State University)

A translu­cent leg kicks out at an orange ball in this com­bined image of merg­ing galaxy clus­ter Abell 520 from NASA’s Hub­ble Space Tele­scope, Chan­dra X-ray Obser­va­tory and the Canada-France Hawaii Telescope.

Explore the false-color hues imposed on the far­away galax­ies. What sto­ries or pat­terns do you see? Leave a note below.

This is not a true image. Astronomers used Chan­dra and the CFHT tele­scope to map the ghostly orange and blue-green blobs of color. These col­ors show areas of dif­fer­ent tem­per­a­tures of hot gas and give an indi­ca­tion of where dark mat­ter lies. A Hub­ble image was then placed within the image to give astronomers an idea of the galax­ies involved in the collision.

First hypoth­e­sized about 80 years ago, dark mat­ter is an unseen force in the Uni­verse. Astronomers don’t know much about dark mat­ter. The bizarre mate­r­ial is not made up of the same mat­ter that makes up stars, plan­ets and humans. But even though it is poorly under­stood, astronomers believe it makes up most of the Universe’s mass.

What excites astronomers most about this image is how it shows the clump­ing of starlight, hot gas and the inter­ac­tion with dark mat­ter in this galaxy clus­ter. The blue-green area, includ­ing the kick­ing leg, is a clump of dark mat­ter left behind after the colos­sal galac­tic wreck. After most galac­tic col­li­sions and merg­ers, galax­ies hang together. Dark mat­ter and galax­ies clump together. They become larger ellip­ti­cal galax­ies. Sci­en­tists expected that here but instead most of the galax­ies seem to be zoom­ing away from each other.

Col­li­sions between galaxy clus­ters, the largest struc­tures in the Uni­verse, offer some clues as to the nature of dark mat­ter. This mas­sive col­li­sion is incred­i­bly dis­tant; about 2.4 bil­lion light-years from Earth toward the con­stel­la­tion of Orion, the myth­i­cal Hunter.

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