How Dark Matter Could Reduce The Fleet Of Galaxies Following The Milky Way

Saturday, September 13, 2014

How Dark Matter Could Reduce The Fleet Of Galaxies Following The Milky Way

How Dark Matter Could Reduce The Fleet Of Galaxies Following The Milky Way:

On either side of the white line in the picture are two models of how dark matter is distributed in a galaxy similar to the Milky Way. At left, non-interacting cold dark matter creates satellite galaxies. At right, dark matter interacting with other particles makes the number of observed satellite galaxies smaller. Credit: Durham University

Funny how small particle interactions can have such a big effect on the neighbors of the Milky Way. For a while, scientists have been puzzled about the dearth of small satellite galaxies surrounding our home galaxy.

They thought that cold dark matter in our galaxy should encourage small galaxies to form, which created a puzzle. Now, a new set of research suggests the dark matter actually interacted with small bits of normal matter (photons and neutrinos) and the dark matter scattered away, reducing the amount of material available for building galaxies.

“We don’t know how strong these interactions should be, so this is where our simulations come in,” stated Celine Boehm, a particle physicist at Durham University who led the research. “By tuning the strength of the scattering of particles, we change the number of small galaxies, which lets us learn more about the physics of dark matter and how it might interact with other particles in the Universe.”

Artist’s conception of the Milky Way galaxy based on the latest survey data from ESO’s VISTA telescope at the Paranal Observatory. A prominent bar of older, yellower stars lies at galaxy center surrounded by a series of spiral arms. The galaxy spans some 100,000 light years. Credit: NASA/JPL-Caltech, ESO, J. Hurt

Dark matter is a poorly understood part of the Universe, which is frustrating for scientists because it (along with dark energy) is believed to make up the majority of our Cosmos. There are several postulated types of it, but the main thing to understand is dark matter is hard to detect (except, in certain cases, through its interactions with gravity.)

This isn’t the only explanation for why the galaxies are missing, the scientists caution. Perhaps the universe’s first stars were so hot that they affected the gas that other stars formed from, for example.

A paper on the research was published in the Monthly Notices of the Royal Astronomical Society and is also available in preprint version on Arxiv.

Source: Royal Astronomical Society

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The National Aeronautics and Space Administration (NASA) is the United States government agency responsible for the civilian space program as well as aeronautics and aerospace research. President Dwight D. Eisenhower established the National Aeronautics and Space Administration (NASA) in 1958 with a distinctly civilian (rather than military) orientation encouraging peaceful applications in space science. The National Aeronautics and Space Act was passed on July 29, 1958, disestablishing NASA's predecessor, the National Advisory Committee for Aeronautics (NACA). The new agency became operational on October 1, 1958.

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Photos of Nature | Nature Photography What is The Universe

Photos of Nature | Nature Photography What is The Universe

Saturday, September 13, 2014