A phase lag between disc and corona in GRMHD simulations of precessing tilted accretion discs

M. Liska*, C. Hesp, A. Tchekhovskoy, A. Ingram, M. van der Klis, S. B. Markoff

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


In the course of its evolution, a black hole (BH) accretes gas from a wide range of directions. Given a random accretion event, the typical angular momentum of an accretion disc would be tilted by ∼60 relative to the BH spin. Misalignment causes the disc to precess at a rate that increases with BH spin and depends on disc morphology. We present general-relativistic magnetohydrodynamic (GRMHD) simulations spanning a full precession period of highly tilted (60), moderately thin (h/r=0.1) accretion discs around a rapidly spinning (a≃0.9) BH. While the disc and jets precess in phase, we find that the disc wind/corona, sandwiched between the two, lags behind by ≳10°. For spectral models of BH accretion, the implication is that hard non-thermal (corona) emission lags behind the softer (disc) emission, thus potentially explaining some properties of the hard energy lags seen in Type-C low frequency quasi-periodic oscillations in X-ray binaries. While strong jets are unaffected by this disc-corona lag, weak jets can stall when encountering the lagging corona at distances r∼100 BH radii. This interaction may quench large-scale jet formation.

Original languageEnglish (US)
Article number102012
JournalNew Astronomy
StatePublished - Jul 2023


  • Accretion, accretion discs
  • Black hole physics
  • Galaxies: jets
  • MHD
  • Methods: numerical

ASJC Scopus subject areas

  • Instrumentation
  • Astronomy and Astrophysics
  • Space and Planetary Science


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