Around the Milky Way, small galaxies orbit around us. These are the rare dwarf satellite galaxies and now, two separate groups of scientists have potentially discovered a new set of these celestial objects thanks to data obtained by the Dark Energy Survey.
Dwarf galaxies are particularly important because not only are they the smallest galaxies in our universe, but scientists believe that they also contain a lot of dark matter, that mysterious stuff that we know exists, but still haven't found proof of yet.
"The large dark matter content of Milky Way satellite galaxies makes this a significant result for both astronomy and physics," says Alex Drlica-Wagner of Fermilab.
Dwarf satellite galaxies have matter that isn't attributed to their stars, suggesting the presence of dark matter. Proof of this dark matter could be found by looking for gamma rays, which occur when particles of dark matter annihilate each other.
These galaxies are also particularly rare because their small size and low number of stars make them difficult to see. These new galaxies have less than 100 stars which, together, are 1 billion times dimmer than the Milky Way. They also contain about a million times less mass than our galaxy and sit 100,000 light-years away from us.
Finding new potential candidates for dwarf galaxies is no small feat, but the Dark Energy Survey has the most high-resolution camera in the world with 570 megapixels; this gives it the ability to see objects up to 8 billion light-years from Earth. Mounted on the Victor M. Blanco telescope in Chile, this camera's mission is to survey the southern sky and provide photos with details we have not yet seen.
Scientists hope that the five-year Dark Energy Survey mission will help them find evidence of dark energy, believing it responsible for the universe's current expansion.
Although the last such survey, the Sloan Digital Sky Survey, which looked at a different part of the sky, found about 20 similar dwarf satellite galaxies, scientists believe that the new one will find many more.
"The Dark Energy Camera is a perfect instrument for discovering small satellite galaxies," says Keith Bechtol of the Kavli Institute for Cosmological Physics at the University of Chicago. "It has a very large field of view to quickly map the sky and great sensitivity, enabling us to look at very faint stars."
Scientists will further study these newly discovered galaxies to confirm their status as dwarf satellites, using observations to determine their size, level of brightness and distance from the Milky Way's center.
