Space

August 31, 2013

NASA’s Chandra Observatory catches giant black hole rejecting material

nasa-chandra
 

Astronomers using NASA’s Chandra X-ray Observatory have taken a major step in explaining why material around the giant black hole at the center of the Milky Way Galaxy is extraordinarily faint in X-rays. This discovery holds important implications for understanding black holes.

New Chandra images of Sagittarius A* (Sgr A*), which is located about 26,000 light-years from Earth, indicate that less than 1 percent of the gas initially within Sgr A*’s gravitational grasp ever reaches the point of no return, also called the event horizon. Instead, much of the gas is ejected before it gets near the event horizon and has a chance to brighten, leading to feeble X-ray emissions.

These new findings are the result of one of the longest observation campaigns ever performed with Chandra. The spacecraft collected five weeks’ worth of data on Sgr A* in 2012. The researchers used this observation period to capture unusually detailed and sensitive X-ray images and energy signatures of super-heated gas swirling around Sgr A*, whose mass is about 4 million times that of the sun.

“We think most large galaxies have a supermassive black hole at their center, but they are too far away for us to study how matter flows near it,” said Q. Daniel Wang of the University of Massachusetts in Amherst, who led of a study published Thursday in the journal Science. “Sgr A* is one of very few black holes close enough for us to actually witness this process.”

The researchers found that the Chandra data from Sgr A* did not support theoretical models in which the X-rays are emitted from a concentration of smaller stars around the black hole. Instead, the X-ray data show the gas near the black hole likely originates from winds produced by a disk-shaped distribution of young massive stars.

“This new Chandra image is one of the coolest I’ve ever seen,” said co-author Sera Markoff of the University of Amsterdam in the Netherlands. “We’re watching Sgr A* capture hot gas ejected by nearby stars, and funnel it in towards its event horizon.”

To plunge over the event horizon, material captured by a black hole must lose heat and momentum. The ejection of matter allows this to occur.

“Most of the gas must be thrown out so that a small amount can reach the black hole”, said Feng Yuan of Shanghai Astronomical Observatory in China, the study’s co-author. “Contrary to what some people think, black holes do not actually devour everything that’s pulled towards them. Sgr A* is apparently finding much of its food hard to swallow.”

The gas available to Sgr A* is very diffuse and super-hot, so it is hard for the black hole to capture and swallow it. The gluttonous black holes that power quasars and produce huge amounts of radiation have gas reservoirs much cooler and denser than that of Sgr A*.

The event horizon of Sgr A* casts a shadow against the glowing matter surrounding the black hole. This research could aid efforts using radio telescopes to observe and understand the shadow. It also will be useful for understanding the effect orbiting stars and gas clouds may have on matter flowing toward and away from the black hole.

NASA’s Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA’s Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra’s science and flight operations from Cambridge, Mass.

The paper is available online at http://arxiv.org/abs/1307.5845.




All of this week's top headlines to your email every Friday.


 
 

 

Headlines July 28, 2014

News: U.S. has lost track of weapons given to Afghanistan - The United States supplied almost three quarter of a million weapons to Afghanistan’s army and police since 2004, but the military cannot track where many of those arms have gone, a new report found. Bill to improve VA has $17 billion price tag - A bipartisan...
 
 

News Briefs July 28, 2014

Marines seek authorization for dolphin deaths The Marine Corps is asking for a five-year authorization from the National Marine Fisheries Service for incidental deaths of bottlenose dolphins during training exercises at a bombing and target range. The Sun Journal of New Bern, N.C., reports that Connie Barclay of the National Oceanic and Atmospheric Administration says...
 
 
Army photograph by David Vergun

Senior leaders explain Army’s drawdown plan

Army photograph by David Vergun No commander is happy when notified that a soldier from his or her command has been identified for early separation. But commanders personally notify those Soldiers and ensure participation in th...
 

 

Northrop Grumman awarded mission support services contract

The U.S. Army awarded Northrop Grumman a cost-plus-fixed-fee contract, with a potential value of $205 million, to continue providing mission logistics services in support of combat brigades training at the National Training Center in Fort Irwin, Calif. The contract covers one base year and two one-year options. Support will include the full range of mission...
 
 
Lockheed Martin photograph by Beth Groom

F-35 Rollout Marks U.S.-Australia Partnership Milestone

Lockheed Martin photograph by Beth Groom Royal Australian Air Force Air Marshal Geoff Brown delivers his remarks at the roll out ceremony for Australia’s first F-35. The official rollout of the first two F-35 Lightning II...
 
 
NASA/JPL-Caltech image

NASA’s Mars spacecraft maneuvers to prepare for close comet flyby

NASA/JPL-Caltech image This graphic depicts the orbit of comet C/2013 A1 Siding Spring as it swings around the sun in 2014. On Oct. 19, the comet will have a very close pass at Mars. Its nucleus will miss Mars by about 82,000 m...
 




0 Comments


Be the first to comment!


Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>