2-6 September 2024
CJD Bonn Castell
Europe/Berlin timezone
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Contribution

CJD Bonn Castell

MAD accretion and AGN jets - observational perspective

Speakers

  • Dr. Tuomas K. SAVOLAINEN

Primary authors

Co-authors

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.