New Black Hole Discovered in Milky Way Galaxy: NASA

A rising tide of high energy X rays was detected from a source towards the centre of our Milky Way Galaxy. This was detected by NASA's Swift satellite. The outburst, produced by a rare X-ray nova, announced the presence of a previously unknown stellar-mass black hole.

Swift was launched in November 2004 and is being managed by Goddard Space Flight Center.

X ray Nova a short lived X ray source that appears suddenly reaches its emission peak in a few days and then fades out over a period of months. The outburst occurs when a torrent of stored gas suddenly rushes toward one of the most compact objects known, either a neutron star or a black hole.

"Bright X-ray novae are so rare that they're essentially once-a-mission events and this is the first one Swift has seen," said Neil Gehrels, the mission's principal investigator, at NASA's Goddard Space Flight Center in Greenbelt, Md. "This is really something we've been waiting for."

Named Swift J1745-26 after the coordinates of its sky position, the nova is located a few degrees from the center of our galaxy toward the constellation Sagittarius. The astronomers predict that the objects are placed at a distance of  20,000 to 30,000 light-years away in the galaxy's inner region.

The astronomers failed to notice the Swift J1745-26 in visible light due to the presence of the thick cloud. The nova pointed in the hard X rays energies above 10,000 electron volts or several thousand times that of visible light on Sept 18, when it reached an intensity equivalent to that of Crab Nebula. Swift J1745-26 was 30 times brighter in soft X-rays than when it was discovered and it continued to brighten.

"The pattern we're seeing is observed in X-ray novae where the central object is a black hole. Once the X-rays fade away, we hope to measure its mass and confirm its black hole status," said Boris Sbarufatti, an astrophysicist at Brera Observatory in Milan, Italy, who currently is working with other Swift team members at Penn State in University Park, Pa.

"Each outburst clears out the inner disk, and with little or no matter falling toward the black hole, the system ceases to be a bright source of X-rays," said John Cannizzo, a Goddard astrophysicist. "Decades later, after enough gas has accumulated in the outer disk, it switches again to its hot state and sends a deluge of gas toward the black hole, resulting in a new X-ray outburst."

The thermal-viscous limit cycle, helps astronomers explain transient outbursts across a wide range of systems, from protoplanetary disks around young stars, to dwarf novae