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Chasing dark matter with the oldest stars in the Milky Way

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Chasing dark matter with the oldest stars in the Milky Way

Post by Dragon on Wed Jan 24, 2018 2:59 pm

Just how quickly is the dark matter near Earth zipping around? The speed of dark matter has far-reaching consequences for modern astrophysical research, but this fundamental property has eluded researchers for years.

In a paper published Jan. 22 in the journal Physical Review Letters, an international team of astrophysicists provided the first clue: The solution to this mystery, it turns out, lies among some of the oldest stars in the galaxy.

"Essentially, these old stars act as visible speedometers for the invisible dark matter, measuring its speed distribution near Earth," said Mariangela Lisanti, an assistant professor of physics at Princeton University. "You can think of the oldest stars as a luminous tracer for the dark matter. The dark matter itself we'll never see, because it's not emitting light to any observable degree—it's just invisible to us, which is why it's been so hard to say anything concrete about it."

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Re: Chasing dark matter with the oldest stars in the Milky Way

Post by Dragon on Wed Jan 24, 2018 3:00 pm


Credit: R. Hurt (SSC), JPL-Caltech, NASA

Barred Spiral Milky Way.

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Last edited by Dragonscryer on Wed Jan 24, 2018 3:02 pm; edited 1 time in total
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Re: Chasing dark matter with the oldest stars in the Milky Way

Post by Dragon on Wed Jan 24, 2018 3:01 pm



Simulation of the evolution of the theorized dark matter halo around the Milky Way galaxy from the galaxy's formation to today.

In our currently favored models of the evolution of the Universe, most of the matter in the Universe is not like the stuff that you, I, this computer or the stars are made out of. Instead, it is a substance called dark matter, so-called because it emits no light and can only interact via gravity.

In this model, when the Universe was very young, the dark matter was relatively smoothly distributed throughout the Universe, But this situation couldnt last, because of gravity. Areas of the Universe which had just very slightly more dark matter than other areas exerted stronger gravity, pulling more dark matter towards them and causing them to get bigger, so they exerted even more gravity... this runaway effect caused all of the dark matter to start clumping together, forming what astronomers call "halos" of dark matter.

 
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