By Alton Parrish (Reporter)
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NASA’s Nuclear Spectroscopic Telescope Array, or NuSTAR, has captured these first, focused views of the supermassive black hole at the heart of our galaxy in high-energy X-ray light. The background image, taken in infrared light, shows the location of our Milky Way’s humongous black hole, called Sagittarius A*, or Sgr A* for short. NuSTAR is the first telescope to be able to focus high-energy X-rays, giving astronomers a new tool for probing extreme objects such as black holes.

Image credit: NASA/JPL-Caltech

In the main image, the brightest white dot is the hottest material located closest to the black hole, and the surrounding pinkish blob is hot gas, likely belonging to a nearby supernova remnant. The time series at right shows a flare caught by NuSTAR over an observing period of two days in July; the middle panel shows the peak of the flare, when the black hole was consuming and heating matter to temperatures up to 180 million degrees Fahrenheit (100 million degrees Celsius).

The main image is composed of light seen at four different X-ray energies. Blue light represents energies of 10 to 30 kiloelectron volts (keV); green is 7 to 10 keV; and red is 3 to 7 keV. The time series shows light with energies of 3 to 30 keV.

The background image of the central region of our Milky Way was taken at shorter infrared wavelengths by NASA’s Spitzer Space Telescope.

 NASA’s newest set of X-ray eyes in the sky, the Nuclear Spectroscopic Telescope Array (NuSTAR), has caught its first look at the giant black hole parked at the center of our galaxy. The observations show the typically mild-mannered black hole during the middle of a flare-up.

These are the first, focused high-energy X-ray views of the area surrounding the supermassive black hole, called Sagittarius A*, at the center of our galaxy. The images were taken by NASA’s black-hole hunter, the Nuclear Spectroscopic Telescope Array, or NuSTAR. Different X-ray energies have been assigned colors to make the composite images shown here.

While Sagittarius A*, or Sgr A* for short, is huge — about 4 million times the mass of our sun — it’s actually smaller than typical black holes situated at the centers of galaxies. Sgr A* is also a lot quieter than other supermassive black holes, only nibbling on fuel, such as stars, gas clouds, comets or asteroids — or not eating at all. The black hole’s eating habits are still largely a mystery, which NuSTAR’s new views will help address. 

Image credit: NASA/JPL-Caltech

In the main image, the brightest white dot is the hottest material located closest to the black hole, and the surrounding pinkish blob is hot gas, likely belonging to a nearby supernova remnant. The time series at right shows a flare caught by NuSTAR over an observing period of two days in July; the middle panel shows the peak of the flare, when the black hole was consuming and heating matter to temperatures up to 180 million degrees Fahrenheit (100 million degrees Celsius).

The main image is composed of light seen at four different X-ray energies. Blue light represents energies of 10 to 30 kiloelectron volts (keV); green is 7 to 10 keV; and red is 3 to 7 keV. The time series shows light with energies of 3 to 30 keV.

“We got lucky to have captured an outburst from the black hole during our observing campaign,” said Fiona Harrison, the mission’s principal investigator at the California Institute of Technology (Caltech) in Pasadena. “These data will help us better understand the gentle giant at the heart of our galaxy and why it sometimes flares up for a few hours and then returns to slumber.”

NuSTAR, launched June 13, is the only telescope capable of producing focused images of the highest-energy X-rays. For two days in July, the telescope teamed up with other observatories to observe Sagittarius A* (pronounced Sagittarius A-star and abbreviated Sgr A*), the name astronomers give to a compact radio source at the center of the Milky Way. Observations show a massive black hole lies at this location. Participating telescopes included NASA’s Chandra X-ray Observatory, which sees lower-energy X-ray light; and the W.M. Keck Observatory atop Mauna Kea in Hawaii, which took infrared images.

Compared to giant black holes at the centers of other galaxies, Sgr A* is relatively quiet. Active black holes tend to gobble up stars and other fuel around them. Sgr A* is thought only to nibble or not eat at all, a process that is not fully understood. When black holes consume fuel — whether a star, a gas cloud or, as recent Chandra observations have suggested, even an asteroid — they erupt with extra energy.

In the case of NuSTAR, its state-of-the-art telescope is picking up X-rays emitted by consumed matter being heated up to about 180 million degrees Fahrenheit (100 million degrees Celsius) and originating from regions where particles are boosted very close to the speed of light. Astronomers say these NuSTAR data, when combined with the simultaneous observations taken at other wavelengths, will help them better understand the physics of how black holes snack and grow in size.

“Astronomers have long speculated that the black hole’s snacking should produce copious hard X-rays, but NuSTAR is the first telescope with sufficient sensitivity to actually detect them,” said NuSTAR team member Chuck Hailey of Columbia University in New York City.

NuSTAR is a Small Explorer mission led by Caltech and managed by NASA’s Jet Propulsion Laboratory in Pasadena for NASA’s Science Mission Directorate in Washington. Orbital Sciences Corporation of Dulles, Va., built the spacecraft. Its instrument was built by a consortium including Caltech; JPL; the University of California (UC) Berkeley; Columbia University; NASA’s Goddard Space Flight Center in Greenbelt, Md.; the Danish Technical University in Denmark; Lawrence Livermore National Laboratory in Livermore, Calif.; and ATK Aerospace Systems of Goleta, Calif.

NuSTAR’s mission operations center is at UC Berkeley, with the Italian Space Agency providing an equatorial ground station located at Malindi, Kenya. The mission’s outreach program is based at Sonoma State University in Rohnert Park, Calif. Goddard manages NASA’s Explorer Program. Caltech manages JPL for NASA.

For information about NASA and agency programs, visit: http://www.nasa.gov .

Contacts and sources:
Alan Buis  
Jet Propulsion Laboratory, Pasadena, Calif.

J.D. Harrington
NASA Headquarters, Washington

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