Nearby ‘Dead’ Galaxy Is Packed With Dark Matter, Astronomers Claim

Posted: Nov 20 2015, 9:00pm CST | by , Updated: Nov 20 2015, 10:18pm CST, in News | Latest Science News


Nearby ‘Dead’ Galaxy Can Provide Clues to Dark Matter
Credit: A. Wetzel and P. Hopkins, Caltech

Astronomers claim that the small galaxy at the edge of our own galaxy has the highest concentration of dark matter in any known galaxy.

Triangulum II is a small, faint galaxy at the edge of our own galaxy, Milky Way. Astronomers have found that the galaxy is on the brink of its demise as it contains just 1,000 stars compared to 100 billion in our own galaxy and only six of its stars are bright enough to be detected through the telescope. 

When assistant professor of astronomy Evan Kirby tried to determine the mass of the galaxy by measuring the speed of the star which reflects gravitational force exerted on the stars, he found something very unusual.

The total mass of the galaxy was much greater than the mass of total stars, implying that the galaxy is packed with denser dark matter. In fact, Kirby suggests that it may be the highest concentration of dark matter in any known galaxy.

“The ratio of dark matter to luminous matter is the highest of any galaxy we know. After I had my measurements I was just thinking – wow.” Kirby said.

Dark matter is something which is not visible or touchable but most of our universe, around 90 percent is made up of the dark matter. And the galaxy Triangulum II may pave the way for directly detecting it. Certain particles of dark matter, known as supersymmetric WIMPs, destroy when collide and produce gamma rays that can be spotted from earth.

Triangulum II is a very quiet galaxy which is run out of its star producing material, meaning the process of star formation is over. Therefore, astronomers are calling it a ‘dead’ galaxy. Detecting gamma rays from its silent conditions will be easier than elsewhere in the universe where these rays will not be clearly visible due to galactic noises.

Another group of scientists is proposing unique explanation that the stars found just outside the Triangulum II are moving faster than the stars closer to the galaxy’s center.

Kirby is planning to measure those findings and says “If it turns out that those outer stars aren’t actually moving faster than the inner one’s, then the galaxy could be in what’s called dynamic equilibrium. That would make it the most excellent candidate for detecting dark matter with gamma rays.” 

Source: Caltech 


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Hira Bashir covers daily affairs around the world.




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