Hubble Detects Smallest Known Dark Matter Clumps
Astronomers have detected dark matter clumps around large- and medium-sized galaxies. Now, using Hubble and a new observing technique, astronomers have found that dark matter forms much smaller clumps than previously known. Phys.Org reports: The researchers searched for small concentrations of dark matter in the Hubble data by measuring how the light from faraway quasars is affected as it travels through space. Quasars are the bright black-hole-powered cores of very distant galaxies. The Hubble images show that the light from these quasars images is warped and magnified by the gravity of massive foreground galaxies in an effect called gravitational lensing. Astronomers used this lensing effect to detect the small dark matter clumps. The clumps are located along the telescope's line of sight to the quasars, as well as in and around the foreground lensing galaxies. Using NASA's Hubble Space Telescope and a new observing technique, astronomers have found that dark matter forms much smaller clumps than previously known. This result confirms one of the fundamental predictions of the widely accepted "cold dark matter" theory. All galaxies, according to this theory, form and are embedded within clouds of dark matter. Dark matter itself consists of slow-moving, or "cold," particles that come together to form structures ranging from hundreds of thousands of times the mass of the Milky Way galaxy to clumps no more massive than the heft of a commercial airplane. (In this context, "cold" refers to the particles' speed.) The Hubble observation yields new insights into the nature of dark matter and how it behaves.
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