Origin of M87 jet precession or wobbling

Determine whether the observed precession or wobbling of the M87 jet is generated by an instability in the plasma flow, such as the Kelvin–Helmholtz instability, or whether the jet is launched in an intrinsically precessing state.

Background

The paper identifies multiple possible causes for the observed position-angle variations and spatially distinct precession modes, including disc tearing, broken discs, tidal torquing, and instabilities associated with accretion processes.

It specifically leaves unresolved whether the precession or wobbling develops after launch through an instability in the plasma flow or is already present in the launched jet. The authors state that disentangling these possibilities will require future high-dynamic-range ground- or space-VLBI observations at millimetre or submillimetre wavelengths.

References

Essentially, the question is whether precession (or wobbling') develops in the jet due to some instability in the plasma flow, e.g. the KH instability, or the jet isborn' to appear precessing.

— RadioAstron space-VLBI imaging of the jet in M87: II. The parsec-scale structure at 4.8 GHz  (2609.18192 - Kravchenko et al., 16 Sep 2026) in Conclusions, paragraph beginning “Precession is a common phenomenon in AGN jets.”