Herschel reveals how much dark matter it takes to form new galaxy

Thursday, February 17, 2011

WASHINGTON - The Herschel Space Observatory has measured how much dark matter is required in order to form a new galaxy.

“If you start with too little dark matter, then a developing galaxy would peter out. If you have too much, then gas doesn’t cool efficiently to form one large galaxy, and you end up with lots of smaller galaxies. But if you have the just the right amount of dark matter, then a galaxy bursting with stars will pop out,” said astronomer Asantha Cooray of the University of California, Irvine.

This right of amount of dark matter turns out to be a mass equivalent to 300 billion of our Suns.

“This remarkable discovery shows that early galaxies go through periods of star formation much more vigorous than in our present-day Milky Way,” said William Danchi, Herschel program scientist at NASA Headquarters in Washington.

Cooray and colleagues used the telescope to measure infrared light from massive, star-forming galaxies located 10 to 11 billion light-years away.

Giant clumps of dark matter act like gravitational wells that collect the gas and dust needed for making galaxies. When a mixture of gas and dust falls into a well, it condenses and cools, allowing new stars to form. Eventually enough stars form, and a galaxy is born.

Herschel mapped the infrared light from collections of very distant, massive star-forming galaxies. This pattern of light, called the cosmic infrared background, is like a web that spreads across the sky.

Because Herschel can survey large areas quickly with high resolution, it was able to create the first detailed maps of the cosmic infrared background.

“This is like looking at a picture in a magazine from a reading distance. You don’t notice the individual dots, but you see the big picture. Herschel gives us the big picture of these distant galaxies, showing the influence of dark matter,” said Jamie Bock of NASA’s Jet Propulsion Laboratory in Pasadena, Calif.

The study appears in the journal Nature, online on Feb. 16. (ANI)

Filed under: Science and Technology

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