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Sagittarius A*: NASA's Chandra Detects Record-Breaking Outburst from Milky Way's Black Hole

  • The largest X-ray flare from the Milky Way's supermassive black hole has been detected.

  • Chandra caught this flare, which was 400 times brighter than the black hole's usual output, in September 2013.

  • Researchers also saw a second large X-ray flare a little over a year later.

  • Two theories are being considered to explain these large flares.

On September 14, 2013, astronomers caught the largest X-ray flare ever detected from the supermassive black hole at the center of the Milky Way, known as Sagittarius A* (Sgr A*). This event, which was captured by NASA's Chandra X-ray Observatory, was 400 times brighter than the usual X-ray output from Sgr A*, as described in our press release. The main portion of this graphic shows the area around Sgr A* in a Chandra image where low, medium, and high-energy X-rays are red, green, and blue respectively. The inset box contains an X-ray movie of the region close to Sgr A* and shows the giant flare, along with much steadier X-ray emission from a nearby magnetar, to the lower left. A magnetar is a neutron star with a strong magnetic field. A little more than a year later, astronomers saw another flare from Sgr A* that was 200 times brighter than its normal state in October 2014.

Astronomers have two theories about what could be causing these "megaflares" from Sgr A*. The first idea is that the strong gravity around Sgr A* tore apart an asteroid in its vicinity, heating the debris to X-ray-emitting temperatures before devouring the remains. Their other proposed explanation involves the strong magnetic fields around the black hole. If the magnetic field lines reconfigured themselves and reconnected, this could also create a large burst of X-rays. Such events are seen regularly on the Sun and the events around Sgr A* appear to have a similar pattern in intensity levels to those.

Sgr A* is about 4.5 million times the mass of our Sun and is located about 26,000 light years from Earth. Researchers have been using Chandra to monitor Sgr A* since the telescope was launched in 1999. Recently, astronomers have been closely watching Sgr A* to see if the black hole would consume parts of a nearby cloud of gas known as G2 and cause flares in X-rays. Due to G2's distance from Sgr A* at the time of the September 2013 flare, however, researchers do not think the gas cloud was responsible for the spike in X-rays.

In addition to the giant flares, the G2 observing campaign with Chandra also collected more data on the magnetar located close to Sgr A*. This magnetar is undergoing a long X-ray outburst, and the Chandra data are allowing astronomers to better understand this unusual object.

The researchers were Daryl Haggard (Amherst College), Frederick K. Baganoff (Massachusetts Institute of Technology), Gabriele Ponti (Max Planck Institute for Extraterrestrial Physics), Craig O. Heinke (University of Alberta), Nanda Rea (University of Amsterdam, Netherlands), Joseph Neilsen (MIT), Michael Nowak (MIT), Sera Markoff (University of Amsterdam), Nathalie Degenaar (University of Michigan), Farhad Yusef-Zadeh (Northwestern University), Douglas A. Roberts (Northwestern), Christaan Brinkerink (University of Nijmegen, Netherlands), Casey J. Law (University of California at Berkeley), Stefan Gillessen (Max Planck Institute for Extraterrestrial Physics), and Riley Connors (University of Amsterdam)

These results were presented at the 225th meeting of the American Astronomical Society meeting being held in Seattle, Washington. NASA's Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, controls Chandra's science and flight operations.

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

Fast Facts for Sagittarius A*:
Credit  NASA/CXC/Amherst College/D.Haggard et al
Release Date  January 5, 2015
Scale  Main Image is 8 arcmin across (about 61 light years); Inset is about 1 arcmin across (about 7.5 light years)
Category  Black Holes, Milky Way Galaxy
Coordinates (J2000)  RA 17h 45m 40s | Dec -29° 00´ 28.00"
Constellation  Sagittarius
Observation Date  Main Image: 43 pointings from September 21, 1999 to May 18, 2009; Inset: Sep 14, 2013
Observation Time  Main Image: 278 hours (11 days 14 hours); Inset: 13 hours 53 min.
Obs. ID  Main Image: 242, 1561, 2943, 2951-2954, 3392, 3393, 3549, 3663, 3665, 4683, 4684, 5360, 5950-5954, 6113, 6363, 6639, 6640-6646, 7554-7759, 9169-9174, 10556; Inset: 15043
Instrument  ACIS
Also Known As Galactic Center
Color Code  Energy: Red (2-3.3 keV), Green (3.3-4.7 keV), Blue (4.7-8 keV)
Distance Estimate  About 26,000 light years
distance arrow
Visitor Comments (9)

I would like to have the best data on the x-ray spectrum from Sagittarius A . Please suggest the best references of your Observatory.

Posted by Yukio Tomozawa on Monday, 09.19.16 @ 16:58pm

Approximately what number of black holes are in the Andromeda galaxy?

Posted by Akash Kundu on Tuesday, 11.24.15 @ 10:06am

Amazing site I must say...

Posted by javeria faraz on Sunday, 10.18.15 @ 10:12am

Black Holes may be Strange Quark Spheres and not holes at all.

Posted by William Switzer on Tuesday, 04.21.15 @ 21:40pm

To some of the commenters below

A sphere is the most compact shape possible, so the immense amount of gravity that a black hole is presumed to have should cause it to be a sphere.

Posted by Jeff on Saturday, 03.7.15 @ 17:24pm

I would think the x-ray flare is more likely to be emitted from material making contact to the accretion disc surrounding the black hole.

Posted by Helen D on Wednesday, 02.25.15 @ 09:29am

I was under the impression that nothing including light can escape a black hole yet here we have a statement that x-rays are emanating from one. Or are the x-rays not FROM the black hole or just the vicinity of same? Confusing.

Posted by Robert H on Saturday, 02.7.15 @ 00:40am

I believe that a Black hole would not take shape or form. I think that A black Hole is a name for a space vacuum that takes matter and energy from both sides from where it stands.

Thank you Gabriela

Posted by Gabriela Garner on Wednesday, 01.14.15 @ 17:30pm

Do black holes have a typical shape, like a sphere or cylinder? Do they take matter from both sides?
Tnx, Don V

Posted by Don Vandervelde on Wednesday, 01.7.15 @ 23:06pm

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Press Room: Sagittarius A*
For Kids: Sagittarius A*
Blog: Sagittarius A*
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