1. Overview of (sub)mm-VLBI Shep Doeleman MIT Haystack Observatory

2. A (sub)mm-VLBI Workshop Important: Broad interest in key science drivers. Timely: – Technical Advances: sensitivity and baseline coverage has reached ‘tipping point’. – New submm facilities coming online will significantly improve current array. – Window for (sub)mm-VLBI may not be open indefinitely. Planning Required: – Complex observations must become more turn-key (calibration protocols, permanent VLBI inst., test protocols, …) – Development and deployment of new instrumentation. – Array-wide scheduling (and pan-chromatic). – Development of new sites (still hard, requires collective effort).

3. Workshop Anatomy Presentations – new instrumentation to be deployed at most sites. – development of next-generation instrumentation. – sites under development and new sites. – techniques and protocols for observations. Discussion – address issues necessary for outline of coherent technical roadmap. – address scheduling issues (frequency, dates, no- jeopardy proposing?) – Assess individual site needs for near-term observations.

4. A Brief History of (sub)mm-VLBI 20th anniversary of 1st 1.3mm VLBI fringes! (112Mb/s)

5. Happy Anniversary

6. A Brief History of (sub)mm-VLBI 20th anniversary of 1st 1.3mm VLBI fringes! (112Mb/s) 1994/5 - 215GHz VLBI between IRAM30m - PdeBure(1) 1999 - failed attempt at 230GHz on ARO/SMT-KittPeak 2001 - 147GHz VLBI on IRAM30m - Metsahovi 2002 - 129/147GHz VLBI on IRAM30m, ARO/SMT, KittPeak, Metsahovi (224Mb/s on TAPE). 2003 - 230GHz VLBI on IRAM30m, PdeBure, ARO/SMT, KittPeak (512/1024Mb/s on DISK) 2006 - failed attempt at 230GHz on CSO-ARO/SMT 2007 - 230GHz VLBI on CARMA(1), ARO/SMT, JCMT/SMA, IRAM30m (4Gb/s) 2009 - 230GHz VLBI on CARMA(2), ARO/SMT, JCMT/SMA (4Gb/s)

7. 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

8. 1.3mm Observations of SgrA* 4630km 4030km 908km Builds on long history of SgrA* VLBI and mmVLBI.

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

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

11. Alternatives to a MBH Most condensations of smaller mass objects evaporate on short timescales. Current obs imply Tevap~500 yrs. Boson Star is a remaining ‘exotic’ possibility where R=Rsch + epsilon. Depends on Boson mass.

12. A Surface or Event Horizon Does SgrA* have a surface? A quiescent surface would radiate. The radius R and dM/dt set the expected NIR flux. NIR limits set dM/dt limits. These are too low to power SgrA*. If no surface then Event Horizon. Broderick & Narayan 2006

13. Model Correlated Flux Density Quiescent disk Models: Radiatively Inefficient Accretion Flow (RIAF) Courtesy Gammie et al and Broderick&Loeb

14. April 2009 SgrA* Observations CARMA - Hawaii

15. Time Variable Structures Variabilty in NIR, x-ray, submm, radio. Probe of metrics near BH, and of BH spin. Violates Earth Rotation aperture synthesis. Use ‘good’ closure observables to probe structure as function of time.

16. Hot Spot Model for SgrA* Flares

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

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

19. 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.

20. 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.

21. Comparison with Jet Models a=0.998,  =25deg Broderick & Loeb (2009)

22. 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

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

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

25. Progression to an Image GR Model7 Stations 13 Stations

26. New Site Timeline to 2011 ASTE + APEX tests at 230GHz in Spring 2010 (4Gb/s). Full array observations in 2011 (8Gb/s + 16Gb/s Burst): ARO/SMT Phased Mauna Kea (CSO + JCMT + SMA) Phased CARMA IRAM 30m APEX/ASTE LMT 2011 VLBI contemporaneous with XMM observations. 345GHz tests in 2011.

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

28. Phasing ALMA for VLBI

29. 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

30. Wide(er)band 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. Correlation on software platforms.

31. 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.

32. 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

33. 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

34. More Science Masers: SiO (J=2-1, J=3-2, J=4-5) HCN (177GHz) Water Methanol Jet Physics Sensitivity: ALMA(50) - ARO/SMT at 4GHz (16Gb/s) 35mJy at 230GHz = 7sigma in 10 seconds. Many more sources

35. 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 <5 years. Higher sensitivity enabling broader science case. 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.

36. 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, Alan Roy 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.