Bridging the Bondi and Event Horizon Scales: 3D GRMHD Simulations Reveal X-shaped Radio Galaxy Morphology

Journal Article · Mon Aug 29 00:00:00 EDT 2022 · The Astrophysical Journal. Letters

DOI:https://doi.org/10.3847/2041-8213/ac7bed· OSTI ID:1983328

Lalakos, Aretaios  ^[1]; Gottlieb, Ore  ^[1]; Kaaz, Nicholas  ^[1]; Chatterjee, Koushik  ^[2]; Liska, Matthew ^[2]; Christie, Ian M. ^[1]; Tchekhovskoy, Alexander  ^[1]; Zhuravleva, Irina  ^[3]; Nokhrina, Elena  ^[4]

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1. Northwestern Univ., Evanston, IL (United States). Center for Interdisciplinary Exploration & Research in Astrophysics (CIERA)
2. Harvard Univ., Cambridge, MA (United States)
3. Univ. of Chicago, IL (United States)
4. Moscow Institute of Physics and Technology (Russia)

X-shaped radio galaxies (XRGs) produce misaligned X-shaped jet pairs and make up ≲10% of radio galaxies. XRGs are thought to emerge in galaxies featuring a binary supermassive black hole (SMBH), SMBH merger, or large-scale ambient medium asymmetry. We demonstrate that XRG morphology can naturally form without such special, preexisting conditions. Our 3D general-relativistic magnetohydrodynamic (GRMHD) simulation for the first time follows magnetized rotating gas from outside the SMBH sphere of influence of radius RB to the SMBH of gravitational radius Rg at the largest scale separation, RB/Rg = 103, to date. Initially, our axisymmetric system of constant-density hot gas contains a weak vertical magnetic field and rotates in the equatorial plane of a rapidly spinning SMBH. We seed the gas with small-scale 2% level pressure perturbations. Infalling gas forms an accretion disk, and the SMBH launches relativistically magnetized collimated jets reaching well outside RB. Under the pressure of the infalling gas, the jets intermittently turn on and off, erratically wobble, and inflate pairs of cavities in different directions, resembling an X-shaped jet morphology. Synthetic X-ray images reveal multiple pairs of jet-powered shocks and cavities. Large-scale magnetic flux accumulates on the SMBH, becomes dynamically important, and leads to a magnetically arrested disk state. The SMBH accretes at 2% of the Bondi rate ($$\dot{M}\simeq 2.4\times {10}^{-3}{M}_{\odot }\,{\mathrm{yr}}^{-1}$$ for M87*) and launches twin jets at η = 150% efficiency. These jets are powerful enough (P_jets ≃ 2 × 10⁴⁴ erg s^-1) to escape along the SMBH spin axis and end the short-lived intermittent jet state, whose transient nature can account for the rarity of XRGs.

• Research Organization: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Oak Ridge Leadership Computing Facility (OLCF)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES). Scientific User Facilities (SUF); National Science Foundation (NSF); National Aeronautics and Space Administration (NASA)
• Grant/Contract Number: AC05-00OR22725; OISE-1743747; AST2107839; AST-1815304; AST-1911080; OAC-2031997; TM1-22005X; NAS8-03060
• OSTI ID: 1983328
• Journal Information: The Astrophysical Journal. Letters, Vol. 936, Issue 1; ISSN 2041-8205
• Publisher: IOP Publishing
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
Astronomy & Astrophysics
High energy astrophysics
Active galactic nuclei
Black hole physics
Jets
Magnetohydrodynamical simulations
General relativity