Over the past few months, NuSTAR has been monitoring the radio galaxy 3C120, in collaboration with ESA’s XMM-Newton, the NRAO’s Very Long Baseline Array (VLBA) system of radio telescopes, and NASA’s Neutron Star Interior Composition Explorer (NICER). 3C120 harbors a supermassive black hole that is launching powerful jets, traveling at close to the speed of light, that travel large distances out of the host galaxy. Working in tandem, NuSTAR and XMM-Newton are able to make precise measurements of the X-rays that are reflected from the innermost regions of the accretion disk of gas that is spiraling into the black hole. These measurements probe the structure of the accretion disk and of the particle acceleration region, known as the corona, which generates the X-ray emission. By obtaining multiple deep X-ray observations, each with a four-day duration exposure, separated by approximately one month, and coordinated with high-resolution radio imaging of the jet, it is possible to trace how knots and other structures launched in the jet are connected to changes in the structure of the inner accretion disk and corona. These observations provide some of the most detailed measurements of how supermassive black hole jets are connected to the small-scale processes happening right outside the black hole event horizon, to answer fundamental questions about exactly how black holes are able to launch jets, and the processes by which energy released from supermassive black holes affects the evolution of the galaxies in which they reside.

Authors: Dan Wilkins (Research Scientist, KIPAC, Stanford University)