Jets with a Twist: The Emergence of FR0 Jets in a 3D GRMHD Simulation of Zero-angular-momentum Black Hole Accretion

Abstract

Spinning supermassive black holes (BHs) in active galactic nuclei magnetically launch relativistic collimated outflows, or jets. Without angular momentum supply, such jets are thought to perish within 3 orders of magnitude in distance from the BH, well before reaching kiloparsec scales. We study the survival of such jets at the largest scale separation to date, via 3D general relativistic magnetohydrodynamic simulations of rapidly spinning BHs immersed into uniform zero-angular-momentum gas threaded by a weak vertical magnetic field. We place the gas outside the BH sphere of influence, or the Bondi radius, chosen to be much larger than the BH gravitational radius, R _B = 10 ^3 R _g . The BH develops dynamically important large-scale magnetic fields, forms a magnetically arrested disk (MAD), and launches relativistic jets that propagate well outside R _B and suppress BH accretion to 1.5% of the Bondi rate, ${\dot{M}}_{{\rm{B}}}$ . Thus, low-angular-momentum accretion in the MAD state can form large-scale jets in Fanaroff–Riley (FR) type I and II galaxies. Subsequently, the disk shrinks and exits the MAD state: barely a disk (BAD), it rapidly precesses, whips the jets around, globally destroys them, and lets 5%–10% of ${\dot{M}}_{{\rm{B}}}$ reach the BH. Thereafter, the disk starts rocking back and forth by angles 90°–180°: the rocking accretion disk (RAD) launches weak intermittent jets that spread their energy over a large area and suppress BH accretion to ≲2% ${\dot{M}}_{{\rm{B}}}$ . Because the BAD and RAD states tangle up the jets and destroy them well inside R _B , they are promising candidates for the more abundant, but less luminous, class of FR0 galaxies.

Keywords

• High energy astrophysics
• Active galactic nuclei
• Black hole physics
• Relativistic jets
• General relativity