Dwarf Satellite Galaxies Discovered by Dark Energy Survey
Scientists have discovered eight celestial objects nearby our Milky Way galaxy, using one of the world's most powerful cameras, the Dark Energy Camera, according to a Fermilab press release. These objects could help scientists dive deeper into the understanding of the nature of dark energy.
Early signs indicate that these objects are most likely dwarf satellite galaxies, in orbit around the Milky Way. Dwarf satellite galaxies are the most condensed form of galaxies, sometimes containing fewer than 1,000 stars, compared to the billions within the Milky Way. These smaller galaxies often orbit larger galaxies, and are thought to be the building blocks that come together to create these larger galaxies.
"This exciting discovery is the product of a strong collaborative effort from the entire DES team," Basilio Santiago, a DES Milky Way Science Working Group coordinator and a member of the DES-Brazil Consortium said. "We've only just begun our probe of the cosmos, and we're looking forward to more exciting discoveries in the coming years.
What makes dwarf satellite galaxies so important is that they are especially rich in dark matter, which holds galaxies together, and makes up 25 percent of the total matter and energy in the universe. This mysterious matter is also an invaluable guide to understanding dark energy, which pushes galaxies apart and makes up an estimated 70 percent of the matter and energy in the universe, and the key to figuring out why the universe is expanding so rapidly.
The team that made the discovery is part of the Dark Energy Survey (DES), which seeks to have a better understanding of dark energy's nature in the universe. The DES takes photographs of hundreds of millions of distant galaxies to seek information on both dark matter and dark energy. These closer dwarf galaxies allow for a more extensive probing for information.
So far, the DES has mapped one-eighth of the night sky with its camera, which has led to the discovery of 17 dwarf galaxy candidates in the last six months alone.
"Just this year, more than 20 of these dwarf satellite galaxy candidates have been spotted, with 17 of those found in Dark Energy Survey data," Alex Drlica-Wagner of the U.S. Department of Energy's (DOE) Fermi National Accelerator Laboratory, one of the leaders of the DES analysis, said. "We've nearly doubled the number of these objects we know about in just one year, which is remarkable."
The DES is locating galaxies that were otherwise too faint to see, and in March it jointly announced with the University of Cambridge that it had discovered nine more of these celestial objects, with two being recently confirmed as dwarf satellite galaxies. Prior to 2015, only about 24 of these galaxies had been discovered.
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