1. The Submillimeter Bump of Sgr A* from GRMHD Simulations Jason Dexter University of Washington With Eric Agol, Chris Fragile and Jon McKinney

2. Sub-mm Sgr A* Precision black hole astrophysics Probe strong gravity! 2Probing Strong Gravity Doeleman et al (2008) ~4 R s !  Yuan et al (2003)

3. Black Hole Shadow Sensitive to details of accretion flow – 3D GRMHD! Bardeen (1973); Dexter & Agol (2009)Falcke, Melia & Agol (2000) 3Probing Strong Gravity

4. Modeling Geodesics from Dexter & Agol (2009) Time-dependent, relativistic radiative transfer Simulation from Fragile et al (2007) Fit images to VLBI data over grid in M tor, i, ξ, t obs Unpolarized; single temperature Probing Strong Gravity4 Schnittman et al (2006)

5. GRMHD Fits to VLBI Data Probing Strong Gravity5 Dexter, Agol & Fragile (2009); Doeleman et al (2008) i=10 degreesi=70 degrees  10,000 km   100 μas 

6. Improved Modeling Sub-mm spectral index (Marrone 2006) Add simulations from McKinney & Blandford (2009); Fragile et al (2009) Two-temperature models (parameter T i /T e ) Joint fits to spectral, VLBI data over grid in M tor, i, a, T i /T e Angle-dependent emissivity (Leung et al 2010) Probing Strong Gravity6

7. Parameter Estimates i = 50 degrees T e /10 10 K = 5.4±3.0 ξ = -23 degrees All to 90% confidence Results agree with Broderick et al (2009) Probing Strong Gravity7 +35 -15 +97 -22 Spin Inclination Electron Temperature Sky Orientation

8. Millimeter Flares Models reproduce observed mm flare duration, amplitude, frequency Strong correlation with accretion rate Not caused by heating from magnetic reconnection Probing Strong Gravity8 Solid – 230 GHz Dotted – 690 GHz

9. Shadow of Sgr A* Probing Strong Gravity9 Shadow may be detected on chile- lmt, smto-chile baselines; otherwise need south pole.

10. Conclusions Fit 3D GRMHD images/light curves of Sgr A* to mm observations Estimates of inclination, sky orientation agree with RIAF fits (Broderick et al 2009) Electron temperature well constrained Reproduce observed mm flares LMT-Chile next best chance for observing shadow Future: polarized emission, tilted disks. Probing Strong Gravity10

11. Comparison to Observed Flares Probing Strong Gravity11 Eckart et al (2008)Marrone et al (2008)

12. Spectra Probing Strong Gravity12

13. Visibility Variance Probing Strong Gravity13

14. Accretion Rate Variability Probing Strong Gravity14

15. RIAF Fits Probing Strong Gravity15 Broderick et al (2009)

16. Event Horizon Telescope Probing Strong Gravity16 UV coverage (Phase I: black) From Shep Doeleman’s Decadal Survey Report on the EHT Doeleman et al (2009)