Search

Powerful relativistic jets in active galactic nuclei (AGN) are believed to be originated from the accretion of material onto the supermassive black hole (SMBH)1. The nearby radio galaxy M87 is one of the best examples of this phenomenon, and the recent detection of a black-hole shadow with the Event Horizon Telescope provided compelling evidence for this paradigm2. However, whether the central SMBH in M87 has a spin or not, a fundamental parameter of a BH along with the mass, remains unconstrained by observations since the appearance of the photon ring is rather insensitive to the spin2-4. A clue to this challenge is to trace the long-term evolution of the innermost jet base where the central BH and accretion disk tightly regulate its flow dynamics. Here we report an extensive analysis of the morphological evolution of the M87 jet nozzle based on 170 high-resolution radio images spanning more than two decades. The ensemble of the data reveals a periodic (a period of 11 years) variation of the jet direction with a peak-to-peak amplitude of ~10 deg on the sky. A successful fit of a precession model to the data as well as general-relativistic magnetohydrodynamic simulations strongly supports the presence of a spinning BH in M87, inducing a Lense-Thirring precession of a misaligned accretion disk by the frame-dragging effect5. Our results suggest that jet precession with a spinning BH can commonly exist in other more distant AGN but had evaded detection due to the small magnitude and long period of position angle variation.

Super-critical accretion is the most powerful episode in nursing the black hole growth and works in several types of objects. Given that the inverse correlation between radio loudness and Eddington ratio, the super-Eddington active galactic nuclei (AGNs) hold the extremely radio-quiet end of AGNs. Regarding the existence of jet in super-Eddington or radio-quiet AGNs, it’s still unclear. Years of studies indicate nearly all types of super-Eddington accreting systems can launch a jet with one exception: no clear evidence to show jet in super-Eddington AGNs. Observations and theoretical works suggest that super-Eddington accretion can drive high-speed wind-like outflows, therefore produce radio emission through synchrotron (shocked wind) and bremsstrahlung mechanisms. However, such a radio-emitting wind has not been observed in super-Eddington systems except for the Galactic micro-quasar SS 433. In principle, high resolution very long baseline interferometry (VLBI) observation can directly map the inner structure of super-Eddington AGNs. Here, we report the discovery of the coupling of jet and radio-emitting winds in a nearby super-Eddington AGN, I Zw1. Its parsec-scale jet exhibits a wiggling, we interpret this as a jet precession. All the features make IZw1 act as a scaled-up version of SS 433. The observations favour that jet can be launched in extremely radio-quiet AGNs and ubiquitous in super-Eddington accreting systems. The jet wiggling or precession can produce a large aperture-angle shock, which emphasises the jet’s contribution to gas feedback. As the jet precession was also discovered in other super-Eddington systems such as SS 433 and V404 Cygni, it is possible that there is a correlation with each other.