Monster black holes sometimes lurk behind gas and dust, hiding from the gaze of most telescopes. But they give themselves away when material they feed on emits high-energy X-rays that NASA’s NuSTAR mission can detect. That’s how NuSTAR recently identified two gas-enshrouded supermassive black holes, located at the centers of nearby galaxies.
Supermassive black holes do not give off any of their own light, hence the word “black” in their name. However, many black holes pull in surrounding material and emit powerful bursts of X-rays. Collectively, these active black holes can be thought of a cosmic choir, singing in the language of X-rays. Their “song” is what astronomers call the cosmic X-ray background.
The European Space Agency’s orbiting XMM-Newton X-ray observatory has proved the existence of a ‘gravitational vortex’ around a black hole. The discovery, aided by NASA’s NuSTAR mission, solves a mystery that has eluded astronomers for more than 30 years and will allow them to map the behaviour of matter very close to black holes.
Japan’s doomed Hitomi observatory peeled back a veil on the inner workings of the Perseus cluster of galaxies before the satellite spun out of control earlier this year, revealing in unprecedented detail how gas heated to millions of degrees behaves around an unseen supermassive black hole, scientists said.
An international team of astronomers used European Southern Observatory telescopes to complement other earth- and space-based instruments as part of the XXL survey of galaxy clusters. The ESO team measured the precise distances to the galaxy clusters, providing the 3-D view of the cosmos required to perform accurate measurements of dark matter and dark energy.