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Astronomers unravel 20-year dark matter mystery with new computer models

Posted on September 11, 2013

Astronomers at The University of Texas at Austin believe they have discovered the answer to a 20-year debate over how the mysterious cosmic “dark matter” is distributed in small galaxies. Graduate student John Jardel and his advisor Karl Gebhardt found that the distribution, on average, follows a simple law of decreasing density from the galaxy’s center, although the exact distribution often varies from galaxy to galaxy. The findings are published today in The Astrophysical Journal Letters.

Astronomers unravel 20-year dark matter mystery with new computer models

The Fornax dwarf galaxy is one of our Milky Way’s neighbouring dwarf galaxies. The Milky Way is, like all large galaxies, thought to have formed from smaller galaxies in the early days of the Universe. These small galaxies should also contain many very old stars, just as the Milky Way does, and a team of astronomers has now shown that this is indeed the case. This image was composed from data from the Digitized Sky Survey 2. Credit: ESO/Digitized Sky Survey 2
Astronomers at The University of Texas at Austin believe they have discovered the answer to a 20-year debate over how the mysterious cosmic “dark matter” is distributed in small galaxies. Graduate student John Jardel and his advisor Karl Gebhardt found that the distribution, on average, follows a simple law of decreasing density from the galaxy’s center, although the exact distribution often varies from galaxy to galaxy. The findings are published today in The Astrophysical Journal Letters.

Dark matter is matter that gives off no light, but that astronomers detect by seeing its gravitational tug on other objects (like stars). Theories abound on what dark matter might be made of—unseen particles, dead stars, and more—but nobody knows for sure. Though mysterious, understanding the nature of dark matter is important, because it makes up most of the matter in the universe. The only way to understand how the cosmos evolved to its present state is to decode dark matter’s role.

For that reason, astronomers study the distribution of dark matter within galaxies and on even larger scales. Dwarf galaxies, in particular, make great laboratories to study dark matter, Jardel says, because they contain up to 1,000 times more dark matter than normal matter. Normal galaxies like the Milky Way, on the other hand, contain only 10 times more dark matter than normal matter.

For the past 20 years, observational astronomers and theorists have debated how dark matter is distributed in galaxies. Observational astronomers, through their studies of telescope data, have argued that galaxies have a fairly uniform distribution of dark matter throughout. Theorists, backed by computer simulations from the 1990s, have argued that dark matter density decreases steadily from a galaxy’s core to its hinterlands. The disagreement is known as the “core/cusp debate.”

 

Read more at: Phys.org

   
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  • Nathanael Vignon

    why is it that Astronomers keep changing there theories, there stories, there discoveries,? and this goes on , and on, and nothing seem to be true. and another thing! how can anyone put a timeline on infinity? The universe has no time . time was created for man himself not the universe don’t you think so.? I think so. because all didn’t just start when he came into existence and went he began to look up. for one thing mans eyes are only about ten megapixels so how can he see 400 billion miles away?

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