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AAS Special Session Getting to the Event Horizon: SgrA*

AAS Special Session Getting to the Event Horizon: SgrA*. SgrA*: Best Case for a SMBH. Stellar orbits approaching within 45 AU. Proper motions < 1km/s: M>10^5 Msol (Backer & Sramek 1999, Reid & Brunthaler 2004) Short time scale X-ray flares (300 sec rise). IF flares with modulation (a>0).

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AAS Special Session Getting to the Event Horizon: SgrA*

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  1. AAS Special SessionGetting to the Event Horizon: SgrA*

  2. SgrA*: Best Case for a SMBH • Stellar orbits approaching within 45 AU. • Proper motions < 1km/s: M>10^5 Msol (Backer & Sramek 1999, Reid & Brunthaler 2004) • Short time scale X-ray flares (300 sec rise). • IF flares with modulation (a>0). Ghez et al 2005 VLT: Genzel et al 2003 Baganoff et al 2001

  3. Accretion Radiation Outflow • GR in strong field regime • Accretion/jet models • Black hole parameters A. Fabian Chandra Web site

  4. Resolving Rsch-scale structures Falcke Melia Agol GR Code 1.3mm VLBI 0.6mm VLBI • SgrA* has the largest apparent Schwarzschild radius of any BH candidate. • New high frequency VLBI confirms existence of Event Horizon scale structure in SgrA*.

  5. Getting to the Event Horizon: SgrA*Session Oral Presentations S. Doeleman: mm/submm VLBI of SgrA* C. Gammie: Numerical models of SgrA* A. Broderick: The nature of SgrA* V. Fish: Future mm/submm VLBI observations. F. Yusef-Zadeh: SgrA* flaring activity. L. Meyer: Keck/VLT NIR properties of SgrA* H. Falcke: Jet models for SgrA* using VLBI and timing information.

  6. Observing an Event Horizon:mm/submm VLBI of SgrA* Shep Doeleman MIT Haystack Observatory

  7. mm/submm VLBI Collaboration MIT Haystack: Alan Rogers, Alan Whitney, Mike Titus, Dan Smythe, Brian Corey, Roger Cappallo, Vincent Fish U. Arizona Steward Obs: Lucy Ziurys, Robert Freund CARMA: Dick Plambeck, Douglas Bock, Geoff Bower Harvard Smithsonian CfA: Jonathan Weintroub, Jim Moran, Ken Young, Dan Marrone, Ray Blundell James Clerk Maxwell Telescope: Remo Tilanus, Per Friberg UC Berkeley SSL: Dan Werthimer Caltech Submillimeter Observatory: Richard Chamberlin MPIfR: Thomas Krichbaum JHU - Applied Physics Labs: Greg Weaver Honeywell: Irv Diegel

  8. 1.3mm Observations of SgrA* 908km 4030km 4630km

  9. SMT-CARMA SMT-JCMT Determining the size of SgrA* OBS = 43as (+14, -8) INT = 37as (+16, -10) 1 Rsch = 10as Doeleman et al 2008

  10. Broderick & Loeb The minimum apparent size. Event Horizon Noble & Gammie

  11. SMT-CARMA SMT-JCMT Caveat: Very Interesting Structures 14 Rsch (140as) Gammie et al

  12. Phased array processors: creating large effective VLBI apertures (with SAO). Technical Advances • Increasing bandwidth of VLBI systems: Burst Mode recorders using COTS. • Designing new VLBI freq. standards (UWA). • Adding new VLBI sites (Chile, Mexico).

  13. A Unique Opportunity“Right object, right technique, right time” • SgrA* presents the largest Event Horizon of any BH candidate - Orbital timescales are minutes. • VLBI at 1.3mm and 0.8mm yields ~2 Rsch resolution for SgrA*. • Technical advances and new facilities now make this possible.

  14. 1.3mm VLBI confirms ~4Rsch diameter for SgrA* • Implies that SgrA* is offset from Black Hole. • submm VLBI is able to directly probe Event Horizon scales and trace time variable structure (complements GRAVITY, Con-X). • Focused development of submm-VLBI capability has now put this important goal within reach. • Planned observations over the next 5 years will address fundamental questions of BH physics. Summary

  15. Session Posters Z. Shen: The Variability of SgrA* at 3mm L. Huang: The submm Emission and Visibility of SgrA* S. Markoff: Jet Lags and Other Signatures of Collimated Outflow in SgrA* T. Do: A NIR Variability Study of the Galactic BH: A Red Noise Source with No Detected Periodicity. J. Dexter: The Appearance of SgrA* from GRMHD Simulations J. Weintroub: A Submillimeter VLBI Array R. Shcherbakov: Constraining the BH Parameters and the Accretion Flow in SgrA* by GR Dynamical and Radiative Modeling A.E.E. Rogers: Optimization of Methods to Detect Periodic Structure in VLBI data.

  16. Alternatives to a MBH Most condensations of smaller mass objects evaporate on short timescales. Remaining possibility: Boson Star R=Rsch + epsilon Depends on Boson mass Maoz 1998

  17. Seeing Through the Scattering OBS deviates from scattering for cm INT  SCAT for mm INT 

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