In a new paper in Monthly Notices of the Royal Astronomical Society (MNRAS) with lead author Shifu Zhu, researchers are able to tease out the physics behind why some rapidly spinning supermassive black holes produce powerful jets and others do not. This is one of those cases where all systems with jets are rapidly rotating, but not all rapidly rotating systems have jets.
When an SMBH and its associated disk of infalling material are rapidly rotating, the moving charged particles can generate a powerful magnetic field. Material caught in the magnetic field can be ejected out along the rotation axes of the system and inject huge amounts of energy into the galaxy’s surroundings.
In this study, 729 quasars with jets were observed in the X-ray using the Chandra, XMM Newton, and ROSAT space telescopes; in radio with the Very Large Array (VLA); and optically with the Sloan Digital Sky Survey (SDSS).
According to Zhu: We found there’s another determining factor of whether a supermassive black hole has jets, something called a black hole corona threaded by magnetic fields. If you don’t have a black hole corona that’s bright in X-rays, it seems like you don’t have powerful black hole jets.
These black hole coronas don’t circle the black hole so much as they lay above and below the accretion disk surrounding the black hole. Zhu goes on to explain: Both a quasar’s powerful jets and bright corona occurring together may be fundamentally driven by magnetic fields.
One of the big take-aways from this research is that quasar jets don’t emerge at the disk but instead come out from higher up in the disk’s corona. Co-author Guang Yang explains: Finding that the X-rays in quasars with jets come from a black hole corona, rather than from the jets, challenges 35 years of thinking about the basic nature of this emission. “It could provide new insight into the physics of these jets.
The more we see of our universe, the more we see our own minor and sometimes major mistakes in our understanding of the universe. This is a minor update that makes it possible to finally understand the sporadic nature of jet creation around rotating SMBHs.
“The Lx-Luv-Lradio relation and corona-disc-jet connection in optically selected radio-loud quasars,” S. F. Zhu et al., 2020 June 20, Monthly Notices of the Royal Astronomical Society (preprint on arxiv.org)