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Overview of (sub)mm-VLBI

Overview of (sub)mm-VLBI. Shep Doeleman MIT Haystack Observatory. A (sub)mm-VLBI Workshop. Important: Broad interest in key science drivers. Timely: Technical Advances: sensitivity and baseline coverage has reached ‘tipping point’.

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Overview of (sub)mm-VLBI

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  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 < 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

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

  9. ARO/SMT-CARMA Resolving Rsch-scale structures 14 Rsch (140as) ARO/SMT-JCMT JCMT-CARMA Gammie et al

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

  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. 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. A Surface or 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. 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. Beam: 0.43x0.21 mas 0.2mas = 0.016pc = 60Rs 1mas/yr = 0.25c

  20. CARMA1-CARMA2 CARMA-ARO/SMT JCMT-ARO/SMT JCMT-CARMA 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. April 2009 M87 1.3mm VLBI Detections

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

  22. 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 Making Progress

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

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

  25. Progression to an Image GR Model 7 Stations 13 Stations

  26. 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. New Site Timeline to 2011

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

  28. Phasing ALMA for VLBI

  29. 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 230/345GHz Rx with ALMA Mixers

  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. 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 Status of Collaboration

  34. 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 More Science

  35. 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. Summary

  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.

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