Subscribe to our free daily newsletters
. 24/7 Space News .




Subscribe to our free daily newsletters



Enigmatic X-Ray Sources May Point To New Class Of Black Holes

illustration only
Boston - Mar 08, 2004
Mysterious, powerful X-ray sources found in nearby galaxies may represent a new class of objects, according to data from NASA's Chandra X-ray Observatory. These sources, which are not as hot as typical neutron-star or black-hole X-ray sources, could be a large new population of black holes with masses several hundred times that of the sun.

"The challenge raised by the discovery of these sources is to understand how they produce so much X-ray power at temperatures of a few million degrees," said Rosanne Di Stefano from the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., and Tufts University in Medford, Mass.

Di Stefano is lead author of a series of papers published in or submitted to The Astrophysical Journal and The Astrophysical Journal Letters.

Until a few years ago, astronomers only knew of two sizes of black holes: stellar black holes, with masses about 10 times the sun, and supermassive black holes located at the centers of galaxies, with masses ranging from millions to billions times the sun. Recent evidence suggests a class of "intermediate-mass" black holes may also exist.

Searching for quasisoft sources may be a new way to identify those X-ray sources most likely to be intermediate-mass black holes," said Albert Kong of the Center for Astrophysics (CfA) and a member of the team.

The enigmatic objects found by the Chandra team are called "quasisoft" sources, because they have a temperature in the range of 1 million to 4 million degrees Celsius.

On the one hand this temperature range is below the 10 million to 100 million-degree gas associated with "hard" X-ray sources, such as neutron stars or stellar-mass black holes.

While on the other hand the quasisoft-source temperatures are hotter than the several hundred-thousand-degree gas associated with "supersoft" X-ray sources due to white dwarfs.

Di Stefano and her colleagues determined the temperatures of individual X-ray emitting objects in four galaxies by measuring their X-ray spectra, or distribution of X-rays with energy. They found that between 15 percent and 20 percent of all detected sources fell in the quasisoft temperature range.

The power output of quasisoft sources is comparable to or greater than that of neutron stars or stellar-mass black holes fueled by the infall of matter from companion stars. This implies the region that produces the X-rays in a quasisoft source is dozens of times larger.

One possibility is the quasisoft sources represent standard neutron stars or stellar black holes where the associated hot gas cloud is, for some as yet unknown reason, much larger than usual.

Or the quasisoft X-rays could be coming from the vicinity of intermediate-mass black holes having masses a hundred or more times greater than the mass of the sun. This would increase the diameter of the event horizon and could explain the larger sizes and lower temperatures associated with quasisoft sources.

As more quasisoft sources are discovered, the types of galaxies in which they reside and where they are located in a galaxy should give astronomers additional clues as to their nature. The present study indicates that they occur in various locations in elliptical as well as spiral galaxies.

Di Stefano and her CfA team observed quasisoft sources in several galaxies with Chandra including M101, M83, M51 and NGC 4697.

Related Links
Chandra at NASA
Chandra at Harvard
SpaceDaily
Search SpaceDaily
Subscribe To SpaceDaily Express

Information Paradox Solved? If So, Black Holes Are "Fuzzballs"
Columbus - Mar 04, 2004
Stephen Hawking and Kip Thorne may owe John Preskill a set of encyclopedias. In 1997, the three cosmologists made a famous bet as to whether information that enters a black hole ceases to exist -- that is, whether the interior of a black hole is changed at all by the characteristics of particles that enter it.



Thanks for being here;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.

SpaceDaily Contributor
$5 Billed Once


credit card or paypal
SpaceDaily Monthly Supporter
$5 Billed Monthly


paypal only






Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News








The content herein, unless otherwise known to be public domain, are Copyright 1995-2016 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement All images and articles appearing on Space Media Network have been edited or digitally altered in some way. Any requests to remove copyright material will be acted upon in a timely and appropriate manner. Any attempt to extort money from Space Media Network will be ignored and reported to Australian Law Enforcement Agencies as a potential case of financial fraud involving the use of a telephonic carriage device or postal service.