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Radiative Models of Sgr A* and M87* from Relativistic MHD Simulations

Radiative Models of Sgr A* and M87* from Relativistic MHD Simulations. Jason Dexter University of Washington / UC Berkeley. With Eric Agol , Chris Fragile and Jonathan McKinney. Sagittarius A*. Jet or nonthermal electrons far from BH Thermal electrons at BH

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Radiative Models of Sgr A* and M87* from Relativistic MHD Simulations

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  1. Radiative Models of Sgr A* and M87* from Relativistic MHD Simulations Jason Dexter University of Washington / UC Berkeley With Eric Agol, Chris Fragile and Jonathan McKinney

  2. Sagittarius A* Jet or nonthermal electrons far from BH Thermal electrons at BH Simultaneous IR/X-ray flares close to BH? no data available no data available Charles Gammie, Rainer Schödel AHAR 2011: The Central Kiloparsec

  3. Millimeter VLBI of SgrA* Doeleman et al. (2008) • Precision black hole astrophysics Gaussian FWHM ~4 Rs! AHAR 2011: The Central Kiloparsec

  4. Black Hole Images & Shadows Bardeen (1973); Dexter & Agol (2009) Broderick & Loeb (2009) • Sensitive to viewing geometry & details of accretion flow • Need accurate theoretical predictions! Dexter et al. (2009, 2010) Falcke, Melia & Agol (2000) AHAR 2011: The Central Kiloparsec

  5. Models of Sgr A* • Semi-analytic: • RIAF or jet • Narayan & Yi (1995), Yuan et al. (2003), Brodericket al. (2009, 2010, 2011), Falcke & Markoff (2000) • Hotspots/expanding blobs • Broderick & Loeb (2006), Eckart et al. (2006), Yusef-Zadeh et al. (2006) • MHD Simulations: • Non-relativistic • Goldston et al. (2005), Chan et al. (2008), Huang et al. (2009) • Axisymmetric or averaged GRMHD • Noble et al. (2007), Moscibrodzka et al. (2009), Hilburn et al. (2009) AHAR 2011: The Central Kiloparsec

  6. GRMHD Models of Sgr A* Moscibrodzka et al. (2009) • 3D, time-dependent GRMHD great for mm Sgr A* • Thick, MRI-driven accretion flow • Insignificant cooling(?) • Synchrotron radiation near BH • Not perfect… • Collisionless plasma (mfp = 104 Rs) • No electrons • Assume constant Ti/Te AHAR 2011: The Central Kiloparsec

  7. Ray Tracing • Assume light rays are geodesics: • geokerr, Dexter & Agol(2009) • 5 (4) Simulations: • Fragile et al. (2007, 2009) • McKinney & Blandford (2009) • Synchrotron emissivity: • Leung et al. (2011) • Joint fits to spectral & VLBI data: • Marrone 2006, Doeleman et al. 2008, Fish et al. 2011 • Parameters: dM/dt, i, a, Ti/Te  Schnittman et al. (2006) AHAR 2011: The Central Kiloparsec

  8. Parameter Estimates +15 -15 • i = 60 degrees • ξ = -70 degrees • Te/1010 K = 6 ± 2 • dM/dt = 3 x 10-9Msun yr-1 • All to 90% confidence All VLBI 2007 Sky Orientation +86 -15 Inclination Electron Temperature Accretion Rate +7 -1 Dexter et al. (2010, 2011) AHAR 2011: The Central Kiloparsec

  9. Millimeter Flares • Correlation with accretion rate • Driven by magnetic turbulence • Models reproduce observed mm flares • IR/X-ray? Solid – 230 GHz (1.3mm) Dotted – 690 GHz (0.4mm) AHAR 2011: The Central Kiloparsec

  10. Black Hole Shadow in Sgr A* 230 GHz Shadow 345 GHz Shadow may be detected on Chile-Mexico baseline (in closure phase too) AHAR 2011: The Central Kiloparsec

  11. M87 7mm Junor et al. (1999) • 1600 MSgr A* at 2000 DSgr A* • Jet launching physics? • Known viewing geometry? Hubble 2cm Kovalev et al. (2007) AHAR 2011: The Central Kiloparsec

  12. M87* Models • Simulation: McKinney & Blandford (2009) • Jet: B2 > ρc2, ujet=ηB2 • Representative models: Disk/jet or jet • Unlike previous models • Can’t have disk peak in radio • Can’t match radio at all Broderick & Loeb ( 2009) AHAR 2011: The Central Kiloparsec

  13. Images & Visibilities • Images are still crescents! • Gaussian size: 36-41 μas • Shadow on Hawaii-Mexico or Mexico-Chile Dexter et al. (2011) AHAR 2011: The Central Kiloparsec

  14. Conclusions • Millimeter images/light curves of Sgr A* and M87* from GRMHD simulations • SgrA* (Dexter et al. 2009, 2010, 2011) • Excellent fits with GRMHD & images are crescents! • Estimates for viewing geometry and physical conditions • Reproduce observed mm flares • Mexico—Chile next best chance for observing shadow • M87 (Dexter et al. 2011) • Disk/jet or jet models • Predict 36-41 μas size, shadow on Hawaii—Chile or Mexico—Chile • Robust results if geometry is correct AHAR 2011: The Central Kiloparsec

  15. Tilted Sgr A* • No reason to expect Sgr A* isn’t tilted • Unconstrained parameters • Best fit images are still crescents • Shadow still visible Shadow AHAR 2011: The Central Kiloparsec

  16. RIAF Fits Dexter et al. (2010, 2011), Broderick et al. (2010) AHAR 2011: The Central Kiloparsec

  17. Shadow in Closure Phase AHAR 2011: The Central Kiloparsec

  18. Visibility Variance AHAR 2011: The Central Kiloparsec

  19. Spectra AHAR 2011: The Central Kiloparsec

  20. Accretion Rate Variability AHAR 2011: The Central Kiloparsec

  21. Event Horizon Telescope From Shep Doeleman’s Decadal Survey Report on the EHT UV coverage (Phase I: black) Doeleman et al (2009) AHAR 2011: The Central Kiloparsec

  22. Comparison to Observed Flares Marrone et al. (2008) Eckart et al. (2008) AHAR 2011: The Central Kiloparsec

  23. Galactic Center Black Hole AHAR 2011: The Central Kiloparsec

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