- evn2024@mpifr.de
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Contribution
MAD accretion and AGN jets - observational perspective
Speakers
- Dr. Tuomas K. SAVOLAINEN
Primary authors
- Dr. Tuomas K. SAVOLAINEN (Aalto Univ.)
Co-authors
- Dr. Wara CHAMANI (Aalto Univ.)
Content
One of the major open questions related to the production of jets by accreting black holes is: why sources with similar accretion powers produce so vastly different jet powers? What are the conditions that are required to produce a powerful jet? If jets are powered by the Blandford-Zjanek mechanism, there are two obvious parameters controlling the jet power besides the black hole mass - black hole spin and the magnetic flux threading it. Since there appears to exist highly spinning black holes without jets, it seems possible that the jet production efficiency depends on whether the black hole has been able to accrete high enough magnetic flux. The highest-efficiency jets in this picture are launched from magnetically arrested disks (MADs). We will discuss a method to test this hypothesis using VLBI core-shift measurements to estimate the jet magnetic flux, and present what we have learned about the MAD systems from such studies over the past decade.