Oscillation Modes of the Inner Torus in MHD
- Slides: 20
Oscillation Modes of the Inner Torus in MHD Simulations of Black-Hole Accretion Disks P. Chris Fragile College of Charleston Collaborators: Omer Blaes (UCSB), Phil Arras (UVa) 10. 19. 06 MIT Workshop on QPOs
Oscillation Modes of the Inner Torus in MHD Simulations of Black-Hole Accretion Disks I. Hydrodynamic Slender Torus Limit II. MRI Turbulence 10. 19. 06 MIT Workshop on QPOs
Hydrodynamic Slender Torus R 0 10. 19. 06 MIT Workshop on QPOs
Lowest Order Modes of Slender Torus Blaes, Arras, & Fragile (2006) 3: 2 frequency ratio? 10. 19. 06 MIT Workshop on QPOs
Lowest Order Modes of Slender Torus Blaes, Arras, & Fragile (2006) -Abramowicz et al. 10. 19. 06 MIT Workshop on QPOs
-Rezzolla et al. Blaes, Arras, & Fragile (2006) Lowest Order Modes of Slender Torus 10. 19. 06 MIT Workshop on QPOs
Blaes, Arras, & Fragile (2006) Lowest Order Modes of Slender Torus 10. 19. 06 MIT Workshop on QPOs
Vertical Epicyclic & Breathing Mode ntu e m mo r la c fi i c pe u g n a m 0. 998 0 Blaes, Arras, & Fragile (2006) Co s t n a nst 10. 19. 06 MIT Workshop on QPOs
Simulations of Oscillation Modes of Slender Torus • Hydrodynamic case – no magnetic fields • Initialize 6 lowest order modes at moderate amplitude 10. 19. 06 MIT Workshop on QPOs
Simulations of Oscillation Modes of Slender Torus ||ρ||2 δρ Vr+Vθ Blaes, Arras, & Fragile (2006) • All modes appear to be captured by at least one diagnostic • Some combination modes are also indicated 10. 19. 06 MIT Workshop on QPOs
QPOs in MRI Turbulent Disks (Shearing Box) Acoustic (p) modes Inertial (g) modes (absent) Arras, Blaes, & Turner (2006) • Hydrodynamic modes in MRI turbulence 10. 19. 06 MIT Workshop on QPOs
Global Simulation of MRI Turbulent Disk Does the inner torus display similar mode behavior to the hydrodynamic slender torus? Hawley & Balbus (2002) 10. 19. 06 MIT Workshop on QPOs
QPOs in MRI Turbulent Disks (Global Simulation) Snapshot of Azimuthally Averaged Density Structure of Inner Torus 10. 19. 06 MIT Workshop on QPOs
Power Spectrum of Global Simulation • Power Spectra of Time Series of Density at Three Points Inside Inner Torus 10. 19. 06 MIT Workshop on QPOs
Power in Different eim Modes • Peaks in density power spectra all correspond to nonaxisymmetric modes m=1 m=2 m=3 m=4 10. 19. 06 MIT Workshop on QPOs
Snapshot of Density in Equatorial Plane 10. 19. 06 MIT Workshop on QPOs
Power in Different eim Modes • Peaks in density power spectra all correspond to nonaxisymmetric modes • Have corotation resonances inside the inner torus. • Might be a manifestation of PPI m=1 m=2 m=3 m=4 10. 19. 06 MIT Workshop on QPOs
Principle PPI Mode Should be Stable 10. 19. 06 MIT Workshop on QPOs
Final Thoughts… • Unclear What This Means for Observed QPO’s in Black Hole X-ray Binaries – Observed QPO’s are not seen in thermal dominant state, nor are they associated with thermal photons in the other states. – Radial pressure gradients might be significant in the flow structures that are responsible for observed QPO’s. • Are there toroidal flow structures in the hard and steep power law states? 10. 19. 06 MIT Workshop on QPOs
Thermal State Hard State? Steep Power Law State? ? ? 10. 19. 06 MIT Workshop on QPOs
