Top: An illustration of NASA's Nuclear Spectroscopic Telescope Array, or NuSTAR, in orbit. The unique school bus-long mast allows NuSTAR to focus high energy X-rays.
Lower-left: A color image from NASA's Hubble Space Telescope of one of the nine galaxies targeted by NuSTAR in search of hidden black holes.
Bottom-right: An artist's illustration of a supermassive black hole, actively feasting on its surroundings. The central black hole is hidden from direct view by a thick layer of encircling gas and dust.
This composite image of a galaxy illustrates how the intense gravity of a supermassive black hole can be tapped to generate immense power. The image contains X-ray data from NASA's Chandra X-ray Observatory (blue), optical light obtained with the Hubble Space Telescope (gold) and radio waves from the NSF's Very Large Array (pink).
Magnetars are dense, collapsed stars (called “neutron stars”) that possess enormously powerful magnetic fields. At a distance that could be as small as 0.3 light years (or about 2 trillion miles) from the 4-million-solar mass black hole in the center of our Milky Way galaxy, the magnetar is by far the closest neutron star to a supermassive black hole ever discovered and is likely in its gravitational grip.
The two magenta spots are blazing black holes first detected at lower-energy X-ray wavelengths by NASA's Chandra X-ray Observatory.
Sagittarius A* is the black hole at the center of the Milky Way galaxy.
X-ray: NASA/UMass/D.Wang et al., IR: NASA/STScI
IN SPACE - JANUARY 6: Bright flares are visible near the event horizon of a super-massive black hole at the center of our galaxy, the Milky Way also known as Sagittarius A in this image released on January 6, 2003. The Chandra X-Ray Observatory created the image, in an exposure lasting two weeks. (Photo by NASA/CXC/MIT/F.K.Baganoff/Getty Images)
IN SPACE - FEBRUARY 25: This NASA composite image of galaxy NGC 3079 was created by combining images from the Hubble Space Telescope and the Chandra X-Ray Observatory on February 25, 2003. Large filaments of gas blown out from the center of the galaxy by 'super winds' from either a black hole or an exploding star, are visible in the Chandra image (blue) superimposed over the Hubble optical spectrum image (red and green). (Photo by NASA/CXC/U. North Carolina/G. Cecil/Getty Images)
Massive Black Hole Implicated in Stellar Destruction (NASA, Chandra, Hubble, 01/04/10)
IN SPACE - NOVEMBER 19: The galaxy NGC6240 is shown in this handout image from the NASA Chandra X-Ray observatory on November 19, 2002. The new x-ray observations of the galaxy have revealed two super-massive black holes at the center of the galaxy. The black holes will eventually merge in a cataclysmic event that will cause warps or gravitational waves in space. (Photo by NASA/CXC/MPE/S.Komossa/Getty Images)
Black Holes Go 'Mano a Mano' (NASA, Chandra, 10/06/09)
NASA's Nuclear Spectroscopic Telescope Array (NuSTAR) recently recorded some of the "biggest and baddest" black holes in nine known galaxies. These monsters are actively devouring material, but their hidden nature makes observing them a challenge. Usually buried underneath a thick blanket of gas and dust, scientists are now able to observe these super massive black holes.
Clear observations were not possible before NuSTAR -- which launched in 2012 -- and has allowed scientists to learn why some black holes only appear obscured and why they are more active than previously thought.
Related: NASA: Black holes make perfect lab for dark matter