"This is an artist's concept of a region very near a black hole. It was made to go along with some of our very first results, where we measured the spin of a supermassive black hole unambiguously for the first time," says Harrison. "NuSTAR's high-energy X-ray vision allowed us to distinguish between models that explain what produces black holes' X-ray emissions, and this information led us to conclude that the observed black hole is rapidly spinning."
"This is a beautiful image, and one of the things we built NuSTAR to do—to make the first map of radioactivity in the remnant of an exploded star," says Harrison. "We spent years developing specialized detectors to have the capability to make this image. From the image, we were able to determine the mechanism that caused the star to explode." NuSTAR data show high-energy X-rays from radioactive material in blue. Non-radioactive materials are red, yellow, and green.
"This result was one of the biggest surprises from NuSTAR. We detected pulsing from an object in a galaxy that everybody had assumed was a black hole, thereby showing it was actually a stellar remnant called a pulsar. At the time, it was by far the brightest pulsar known. At first nobody believed it, but the signal was so strong and clear." Since this discovery two other extremely bright pulsars have been found—prompted by NuSTAR's discovery. High-energy X-rays from the pulsar are seen in pink.
"With NuSTAR, we see flaring, active regions of the sun where high-energy particles are being created. NuSTAR was built as an astrophysics mission, not to study the sun," says Harrison. "People thought we were crazy at first to study the sun. But now, by studying the sun with much greater sensitivity in high-energy X-rays, we are contributing to the field of solar physics."
"This image illustrates another job NuSTAR was designed to do—to find hidden black holes buried by dust and gas. This is a wonderful result, led by two graduate students. What they found is that there is a thick layer of gas and dust hiding the active black hole in the galaxy NGC 1448 from our sight."
Five years ago today, on June 13, 2012, Fiona Harrison, the Benjamin M. Rosen Professor of Physics at Caltech and principal investigator of NASA's NuSTAR mission watched with her team as their black-hole-spying spacecraft was launched into space aboard a rocket strapped to the belly of an aircraft. The launch occurred over the Kwajalein Atoll in the Marshall Islands, which is hard to reach, so many members of the team anxiously followed the launch from the mission's operations center at UC Berkeley, unsure of what NuSTAR would see.
Five years later, we sat down with Harrison, who is also the Kent and Joyce Kresa Leadership Chair of the Division of Physics, Mathematics and Astronomy, to get her take on five of the mission's many iconic images and artist concepts—ranging from our flaring sun to distant, buried black holes. NuSTAR is the first telescope capable of focusing high-energy X-rays—and it has taken the most detailed images of the sky in this energy regime to date.