Using NASA's Nuclear Spectroscopic Telescope Array (NuSTAR) and the ESA's XMM-Newton, astronomers were able to observe the black hole that lies at the center of the galaxy NGC 1365. The object was found to be spinning nearly as fast as physics will allow, providing researchers with new information about how black holes behave.
"This is hugely important to the field of black hole science," said Lou Kaluzienski, a NuSTAR program scientist at NASA Headquarters.
The measurements, to be published in the journal Nature, also provide clear evidence for Einstein's theory of general relativity. The data shows that X-rays around the black hole are being warped by the object's high gravity.
"We can trace matter as it swirls into a black hole using X-rays emitted from regions very close to the black hole," said Fiona Harrison, coauthor of a new study, NuSTAR principal investigator of the California Institute of Technology in Pasadena. "The radiation we see is warped and distorted by the motions of particles and the black hole's incredibly strong gravity."
Both the NuSTAR and XMM-Newton telescopes were needed to penetrate the gas clouds that obscure NGC 1365's center. NuSTAR detects high-energy X-ray radiation, while the XMM-Newton detects lower-energy X-rays. By simultaneously observing the X-rays emitted by iron in the black hole's accretion disc, the telescopes were able to determine that the X-ray distortion was coming from the black hole instead of gas clouds. This means that astronomers can now use iron signature distortions to measure black hole spin rates.
"If I could have added one instrument to XMM-Newton, it would have been a telescope like NuSTAR," said Norbert Schartel, XMM-Newton Project Scientist at the European Space Astronomy Center. "The high-energy X-rays provided an essential missing puzzle piece for solving this problem."
(Image courtesy NASA/JPL-Caltech)