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3D Simulations of Tilted Black-hole Accretion: Jets, Precession, and Quasi-periodicity

Detail Summary
Date 2 November 2017
Time 12:00 -13:00
Casper Hesp

Black hole (BH) accretion naturally produces relativistic jets that transport energy from BHs to distances over millions times larger. Importantly, most accretion flows are tilted with respect to their BH, because the gas infalling from large distances is unaware of the direction of the BH spin. It has been argued that tilted accretion could give rise to quasi-periodic oscillations (QPOs), observed in BH accretion across many wavelengths (associated with disks and jets). Spinning black holes induce Lense-Thirring (LT) precession in particles on tilted orbits, i.e., periodic behavior. While LT precession is a commonly cited explanation for QPOs, it remains poorly explored in simulations of general-relativistic magnetohydrodynamics. Using a newly developed simulation code, we explored a completely new regime of BH accretion and jet formation. For the first time, we investigated numerically whether periodicity could result from tilted accretion and associated jets. For example, it is unknown whether tilted disks are capable of producing stable jets (allowing for quasi-periodicity). Also, it is unknown whether jets follow the BH spin axis or precess along with the accretion disk. I will discuss the analyses and implications of these simulations for the study of BH accretion, helping to bridge observations and theory.