Big Discovery, Tiny Black Hole

Black hole’s have often been the focus of scientific endeavor, but mostly for the size and subsequent massive destructive capability. Now, however, it’s the smaller end of the scale of black hole’s that have captured astronomer’s attention.

Nikolai Shaposhnikov and Lev Titarchuk of NASA’s Goddard Space Flight Center in Greenbelt, Md, are behind the new discovery which has found the lightest known black hole. With a mass of only 3.8 times that of our own Sun and a diameter of only 15 miles, this black hole could shed some well deserved light on the minimum size a black hole can reach.

"This black hole is really pushing the limits. For many years astronomers have wanted to know the smallest possible size of a black hole, and this little guy is a big step toward answering that question," says lead author Shaposhnikov.

The pair used a new method to determine the black hole’s mass. To quote from the Goddard presss release, ‘It uses a relationship between black holes and the inner part of their surrounding disks, where gas spirals inward before making the fatal plunge. When the feeding frenzy reaches a moderate rate, hot gas piles up near the black hole and radiates a torrent of X-rays. The X-ray intensity varies in a pattern that repeats itself over a nearly regular interval. This signal is called a quasi-periodic oscillation, or QPO.’

Shaposhnikov and Titarchuk tested their QPO method on three black holes whose masses had already been previously measured. In their new paper, published in the Astrophysical Journal, they pushed their testing to seven other black holes, three of which had well-determined masses. "In every case, our measurement agrees with the other methods," says Titarchuk. "We know our technique works because it has passed every test with flying colors."

This naturally gives considerable credence to their new discovery.

At some point a dying star – upon death – will produce a neutron star instead of a black hole. Astronomers currently believe this boundary to be somewhere between 1.7 and 2.7 solar masses. Knowing this boundary is important for fundamental physics, as it shows scientists the behavior of matter when, according to Goddard, ‘it is scrunched into conditions of extraordinarily high density.’

Think that because it’s smaller than its bigger cousins inhabiting the center of our galaxy? You’d be wrong! Smaller black holes like this one actually exert a greater tidal force than a larger black hole – presumably because the same forces are being compacted in to such a smaller area. "If you ventured too close to J1650’s black hole, its gravity would tidally stretch your body into a strand of spaghetti," says Shaposhnikov.

Posted by Josh Hill.

Links:

http://www.physorg.com/news126276040.html

http://sciencenow.sciencemag.org/cgi/content/full/2008/401/2