BLACK HOLE HIDING IN GALAXIES
Hiding in the least likely place in space are relatively “skinny galaxies”, there has been located six large black holes. This discovery has demonstrated that gigantic black holes can hide anywhere in the galaxies. Contrary to what astronomers think, the galastic bulges are central concentration of stars, not required for black holes to grow. Milky Way, like most spiral galaxies has such a bulge. The bulge feeds binge eat by the black holes in many large galaxies. It creates a chaotic scene of high-speed consumption and copious radiation.
Smaller and thinner galaxies without bulges show little evidence for super-massive black holes. Galactic obesity isn’t the only path to the black hole generation according to new observation from the Spitzer Space. “This finding challenges the current paradigm”, said Shobita Satyapal of the George Mason University in Fairfax, Virginia. “The fact that galaxies without bulges have black holes means that the bulges cannot be the determining factor.” Satyapal presented the research at a meeting of the American Astronomical Society.
The theory is that dark matter, an invisible substance thought to account for about 85 percent of all matter in the universe, might play a role in the early development of super-massive black holes. The dormant black hole at the center of our galaxy weighs several million times more than the mass of the sun. In more active galaxies, black holes can surpass a billion solar masses. “Scientists reasoned that somehow the formation and growth of galaxy bulges and their central black holes are intimately connected”, Satyapal said.
Astroners are questioning the conventional thinking after a few recent studies. In 2003, scientists discovered a relatively “lightweight” super-massive black hole in a bulge-less galaxy. And even more recently, Satyapal and her team spotted another super-massive black hole lurking in a similarly svelte galaxy. Now, Satyapal and her colleagues have turned up six more monstrous black holes in thinner galaxies with minimal bulges.
Satyapal suggests these black holes were only recently detected because they have been shrouded by their dusty abodes. Galaxies with such minimal midsections tend to be extremely dusty. Infrared light can penetrate the dust, meaning Spitzer could unmask the black holes with its infrared capabilities. “A feeding black hole spits out high-energy light that ionizes much of the gas in the core of the galaxy”, Satyapal said.
Perhaps, Satyapal speculates, the missing piece of the black-hole puzzle is dark matter. Early on in the galaxy’s life, this invisible matter might, somehow, set the mass of the black hole. Other theorists have figured in recent years that dark matter was integral to galaxy information.
“Maybe the bulge was just serving as a proxy for the dark matter mass”, Satyapal said. So the amount of dark matter is “the real determining factor behind the existence and mass of a black hole in a galaxy’s center.”
This entry was posted on Wednesday, January 16th, 2008 at 8:26 am and is filed under Space Agency News. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.
