1. The Event Horizon Telescope: a (sub)mm-VLBI network for imaging super massive black holes Shep Doeleman MIT Haystack Observatory

2. mm/submm VLBI Collaboration MIT Haystack: Alan Rogers, Vincent Fish, entire staff. U. Arizona Steward Obs: Lucy Ziurys, Robert Freund CARMA: Dick Plambeck, David Woody, Geoff Bower Harvard Smithsonian CfA: Jonathan Weintroub, Jim Moran James Clerk Maxwell Telescope: Remo Tilanus, Per Friberg UC Berkeley SSL: Dan Werthimer Caltech Submillimeter Observatory: Richard Chamberlin MPIfR: Thomas Krichbaum ASIAA: Paul Ho, Makoto Inoue NAOJ: Mareki Honma IRAM: Michael Bremer NRAO: John Webber, Ray Escoffier, Rich Lacasse UMass: Neal Erickson, Gopal Narayanan History: Backer, Lo, Rogers, Krichbaum, Jauncy, Marcaide, Shen, Bower.

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

4. Resolving Rsch-scale structures Gammie et al 14 Rsch (  as)  ARO/SMT-CARMA ARO/SMT-JCMT JCMT-CARMA

5. Beam: 0.43x0.21 mas 0.2mas = 0.016pc = 60R s 1mas/yr = 0.25c VLBA Movie of M87 @ 43 GHz (7 mm) Craig Walker et al. 2008 More luminous class of AGN with 2000x more massive central BH, and core detected in TeV with FERMI.

6. April 2009 M87 1.3mm VLBI Detections CARMA1-CARMA2 CARMA-ARO/SMT JCMT-CARMA JCMT-ARO/SMT Resolved component is > 300  as Compact component is 35  as FWHM, or ~ 4.5 Rsch. Apparent size of ISCO is 7.35 Rsch and Apparent size of EH is 5.2 Rsch. Jet genesis, TeV emission.

7. Hot Spot Model for SgrA* Flares

8. Observing Black Hole Orbits with Closure Phase Doeleman et al 2009

9. Polarization Signatures at the Event Horizon Fish et al 2009

10. Making Progress Big Questions Is there an Event Horizon? Does GR hold near BH? How are jets launched? How does matter accrete/outflow near a BH? Essential Requirements Baseline coverage: Develop new sites Sensitivity: new receivers (dual pol) phased arrays wideband recording

11. Event Horizon Telescope Phase 1: 7 TelescopesPhase 2: 10 Telescopes Phase 3: 13 Telescopes

12. Adding ALMA Adding Telescopes Adding LMT Hawaii, CARMA, SMT

13. Progression to an Image GR Model7 Stations 13 Stations

14. Hawaii Phased Array Success (CSO+JCMT+SMA)-CARMA

15. Phasing ALMA for VLBI

16. 230/345GHz Rx with ALMA Mixers Use ALMA development to build sideband separating, dual pol, high sensitivity receivers (ALMA bands 6,7). Developing project with UMass to replace 230GHz Rx at JCMT using ALMA mixer/preamps: Tsys improves by x2.5 BW improves by x4 Dual pol Target installation date: Winter 2011

17. Wideband VLBI Systems Currently at 4Gb/s Continuous 8Gb/s by mid-2010 Burst Mode: using parallel DBE’s and data buffering in RAM to reach 16Gb/s for 60 sec bursts.

18. New Frequency Standards Sapphire Oscillator: – Factor of 10-100 times more stable than Hmaser (T~1-100sec). – Plan to have CSO at Haystack by Spring 2010 in collaboration with UWA. Modified Masers: – Use of best Quartz crystals in H masers to reduce phase noise.

19. EHT Phases: Phase I: 7 station 8Gb/s array ALMA phasing, preliminary Rx/LO work, new frequency standards, new site studies, operations. 2010 -- 2014 Phase II: 10 station 32Gb/s dual-pol array Activate SEST, equip S.Pole, new frequency standards, install new 0.8/1.3mm dual-pol Rx, increase bandwidth of VLBI backends/recorders, relocate ATF dishes, operations. 2015 -- 2018 Phase III: 12 station array up to 64Gb/s install new dishes, array operations for 5 years. 2019 -- 2024

20. Status of Collaboration Haystack: Recorder and Digital Backend Frequency Standards ALMA Phasing Organization of observations Harvard-CfA: Phased Array development SMA support ALMA Phasing U. Arizona/ARO: SMTO support Test observations CARMA: Phased Array work Site support ASIAA: H-maser cost-share JCMT/CSO: Telescope support. NAOJ: ASTE support MPIfR-Bonn Plateau de Bure/IRAM 30m APEX support IRAM: IRAM site support Plateau de Bure phasing NRAO: ALMA Phasing RDBE + Mark5c UC Berkeley: DBE + CARMA phasing

21. 20 yr anniversary of first 1mm VLBI fringes

22. Summary 1.3mm VLBI confirms Event Horizon scale structure in SgrA* and M87 Imaging the Event Horizon and observing BH orbits are within reach in <10 years. Science/Technical advances: rapid change. detections, tech. validation, team, sites. Assembling strong international collaboration. Competitive with (and complementary to) much larger space-based mission (e.g., IXO). Touches on almost all aspects of radio/mm/submm communities. All the ingredients for the EHT exist.