Dark matter is the elusive substance comprising approximately 23 percent of all the mass in our universe which has, so far, eluded scientists’ exhaustive attempts to directly detect the substance. Now, new NASA data has discovered dark matter makes the most massive spiral galaxies spin far faster than expected.
An average spiral galaxy, like the Milky Way, spins at speeds of 468,000mph (753,172kmh).
Super spirals are extreme by many measures. They break the records for rotation speeds
Dr Patrick Ogle
New research has now found the most massive spiral galaxies spin faster than expected.
These “super spirals,” weighing up to 20 times more than the Milky Way, spin at a rate of up to three times faster because of dark matter.
In addition to being more massive than the Milky Way, super spirals also brighter and larger in physical size.
Super spirals were discovered as an important new class of galaxies while studying data from the Sloan Digital Sky Survey (SDSS) as well as NASA’s Extragalactic Database (NED).
NASA scientist Dr Patrick Ogle of the Space Telescope Science Institute, said: “Super spirals are extreme by many measures,”
“They break the records for rotation speeds.”
Dr Ogle’s paper presents new data on the rotation rates of super spirals collected with the Southern African Large Telescope (SALT), the largest single optical telescope in the southern hemisphere.
Data from NASA’s Wide-field Infrared Survey Explorer (WISE) mission was employed for measuring the galaxy masses in stars and star formation rates.
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Professor Tom Jarrett of the University of Cape Town added: “This work beautifully illustrates the powerful synergy between optical and infrared observations of galaxies, revealing stellar motions with SDSS and SALT spectroscopy, and other stellar properties—notably the stellar mass or ‘backbone’ of the host galaxies—through the WISE mid-infrared imaging.”
Theory suggests super spirals spin rapidly because they are located within incredibly large clouds, or halos, of dark matter.
Dark matter has been linked to galaxy rotation for decades.
Legendary astronomer Dr Vera Rubin pioneered work on galaxy rotation rates, illustrating how spiral galaxies rotate faster than if their gravity were solely due to the constituent stars and gas.
Her work showed how an additional, invisible substance known as dark matter must influence galaxy rotation.
A spiral galaxy of a given mass in stars is expected to rotate at a certain speed.
But Dr Ogle’s team has discovered super spirals significantly exceed the anticipated rotation rate.
Super spirals also reside in larger than average dark matter halos.
The most massive halo that Ogle measured contains enough dark matter to weigh at least 40 trillion times as much as our Sun.
That amount of dark matter would normally contain a group of galaxies rather than a single galaxy.
Dr Ogle added: ”It appears that the spin of a galaxy is set by the mass of its dark matter halo,” Ogle explains.
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