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NASA X-ray Telescopes Find Black Hole May Be a Neutrino Factory

For Release: November 13, 2014


Perseus Virgo
Credit: NASA/CXC/Univ. of Wisconsin/Y.Bai. et al.
Press Image and Caption

The giant black hole at the center of the Milky Way may be producing mysterious particles called neutrinos. If confirmed, this would be the first time that scientists have traced neutrinos back to a black hole.

The evidence for this came from three NASA satellites that observe in X-ray light: the Chandra X-ray Observatory, the Swift gamma-ray mission, and the Nuclear Spectroscopic Telescope Array (NuSTAR).

Neutrinos are tiny particles that carry no charge and interact very weakly with electrons and protons. Unlike light or charged particles, neutrinos can emerge from deep within their cosmic sources and travel across the universe without being absorbed by intervening matter or, in the case of charged particles, deflected by magnetic fields.

The Earth is constantly bombarded with neutrinos from the sun. However, neutrinos from beyond the solar system can be millions or billions of times more energetic. Scientists have long been searching for the origin of ultra-high energy and very high-energy neutrinos.

"Figuring out where high-energy neutrinos come from is one of the biggest problems in astrophysics today," said Yang Bai of the University of Wisconsin in Madison, who co-authored a study about these results published in Physical Review D. "We now have the first evidence that an astronomical source – the Milky Way’s supermassive black hole – may be producing these very energetic neutrinos."

Because neutrinos pass through material very easily, it is extremely difficult to build detectors that reveal exactly where the neutrino came from. The IceCube Neutrino Observatory, located under the South Pole, has detected 36 high-energy neutrinos since the facility became operational in 2010.

By pairing IceCube's capabilities with the data from the three X-ray telescopes, scientists were able to look for violent events in space that corresponded with the arrival of a high-energy neutrino here on Earth.

"We checked to see what happened after Chandra witnessed the biggest outburst ever detected from Sagittarius A*, the Milky Way's supermassive black hole," said co-author Andrea Peterson, also of the University of Wisconsin. "And less than three hours later, there was a neutrino detection at IceCube."

In addition, several neutrino detections appeared within a few days of flares from the supermassive black hole that were observed with Swift and NuSTAR.

"It would be a very big deal if we find out that Sagittarius A* produces neutrinos," said co-author Amy Barger of the University of Wisconsin. "It's a very promising lead for scientists to follow."

Scientists think that the highest energy neutrinos were created in the most powerful events in the Universe like galaxy mergers, material falling onto supermassive black holes, and the winds around dense rotating stars called pulsars.

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The team of researchers is still trying to develop a case for how Sagittarius A* might produce neutrinos. One idea is that it could happen when particles around the black hole are accelerated by a shock wave, like a sonic boom, that produces charged particles that decay to neutrinos.

This latest result may also contribute to the understanding of another major puzzle in astrophysics: the source of high-energy cosmic rays. Since the charged particles that make up cosmic rays are deflected by magnetic fields in our Galaxy, scientists have been unable to pinpoint their origin. The charged particles accelerated by a shock wave near Sgr A* may be a significant source of very energetic cosmic rays.

The paper describing these results is available online. 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.

An interactive image, a podcast, and a video about these findings are available at:

For Chandra images, multimedia and related materials, visit:

Media contacts:
Janet Anderson
Marshall Space Flight Center

Megan Watzke
Chandra X-ray Center, Cambridge, Mass.

Visitor Comments (6)

That s pretty cool that you can see a supermassive black hole in the image above. I had thought that they were objects that absorbed all light.
As far as determining the distance across of the Sagitarius A being 91 light years, I think the calculation can be made with simple geometry since they know the distance to the object as approximately 26k light years and the angle it takes up on the sky.

Posted by Kaptain Petro on Monday, 05.11.15 @ 15:47pm

So does the fact that the x-rays arrived before the neutrinos prove that neutrinos travel slower than the speed of light?

Posted by P Buck on Tuesday, 05.5.15 @ 07:51am

Sgr A is approx. 26000 LY from Earth. The 91 LY means that the area of space in the picture is about 91 LY across.

Posted by Barry R Ford on Wednesday, 01.14.15 @ 10:43am

This light, in other words, these photons were emitted by the star 91 years ago.
Now the photon particle of light travels at the speed of light, so the distance it travels is 91 light years and hence we can see it.
What we are seeing is, light emitted by the star, 91 years ago and not now.
To see the stars condition at this moment, we need to wait for another 91 years.

Posted by swaroop joshi on Sunday, 01.4.15 @ 11:09am

I'm not a scientist, and have some questions myself. But I believe that what the measurement you referring to describes is the distance that is pictured ie, what we're looking at is 91 light years across. Cuz the thing we're looking at is 26,000 light years away, so the image of 91 light years of space at the center of our galaxy certainly didn't take only 91 years to get HERE it took 26,000. Any astrophysicist wanna chime in? Keep... looking up

Posted by Kylen on Monday, 12.22.14 @ 23:58pm

The Fast Facts for Sagittarius A are very interesting. It is stated that the Image is about 12 arcmin across about 91 light years .

Can somebody educate me as to how the distance of 91 light years has been measured. The fastest known speed anything can travel in the universe is the LIGHT a speed of 1,86,000 miles per sec. If the light travelled at this speed to show the image to the scientists, it would have taken 91 years. I always wonder how the distances of millions of light years are measured.

Posted by D. S. R. Murty on Tuesday, 11.18.14 @ 07:58am

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