Particle acceleration and the origin of X-ray flares in GR MHD simulations of Sgr A

David Ball, Feryal Özel, Dimitrios Psaltis, Chi Kwan Chan

Research output: Contribution to journalArticlepeer-review

74 Scopus citations


Significant X-ray variability and flaring has been observed from Sgr A but is poorly understood from a theoretical standpoint. We perform general relativistic magnetohydrodynamic simulations that take into account a population of non-thermal electrons with energy distributions and injection rates that are motivated by PIC simulations of magnetic reconnection. We explore the effects of including these non-thermal electrons on the predicted broadband variability of Sgr A and find that X-ray variability is a generic result of localizing non-thermal electrons to highly magnetized regions, where particles are likely to be accelerated via magnetic reconnection. The proximity of these high-field regions to the event horizon forms a natural connection between IR and X-ray variability and accounts for the rapid timescales associated with the X-ray flares. The qualitative nature of this variability is consistent with observations, producing X-ray flares that are always coincident with IR flares, but not vice versa, i.e., there are a number of IR flares without X-ray counterparts.

Original languageEnglish (US)
Article number77
JournalAstrophysical Journal
Issue number1
StatePublished - 2016


  • Acceleration of particles
  • Accretion
  • Accretion disks
  • Black hole physics
  • Magnetic reconnection - Magnetohydrodynamics (MHD)
  • Radiative transfer

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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