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Current mm interferometers

Current mm interferometers. Sébastien Muller Nordic ARC Onsala Space Observatory Sweden. Turku Summer School – June 2009. Current mm interferometers: few facts. - Mm interferometry = Young technique PdBI: early 90s SMA dedication: 2003. PdBI milestones. Design started in 1979

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Current mm interferometers

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  1. Current mm interferometers Sébastien Muller Nordic ARC Onsala Space Observatory Sweden Turku Summer School – June 2009

  2. Current mm interferometers: few facts - Mm interferometry = Young technique PdBI: early 90s SMA dedication: 2003

  3. PdBI milestones • Design started in 1979 • First antenna completed in 1987 • 3 antennas interferometer observations • opened for guest observers 1990 • First fringes at 230 GHz 1995 • 5 antennas configuration 1996 • 6 antennas configuration 2002 • New generation receivers 2007 • & extension of the tracks • 350 GHz receivers 2009… • Broad-band correlator

  4. SMA milestones

  5. Current mm interferometers: few facts - Mm interferometry = Young technique PdBI: early 90s SMA dedication: 2003 - Few mm interferometers, mostly in the Northern hemisphere

  6. Current mm interferometers: few facts - Mm interferometry = Young technique PdBI: early 90s SMA dedication: 2003 - Few mm interferometers, mostly in the Northern hemisphere - Small array Nant < 15 limited instantaneous uv-coverage -> super-synthesis - Limited total collecting area - High altitude site for dry and stable atmosphere

  7. Altitude = 2550m N ant = 6 D = 15m Area = 1060 m2 Altitude = 1340m N ant = 6 D = 10m Area = 471 m2 Altitude = 2200m N ant = 15 D = 6/10m Area = 772 m2 Altitude = 4080m N ant = 8 D = 6m Area = 226 m2 Altitude = 5060m N ant = 50 D = 12m Area = 5652 m2

  8. What did the current generation of mm interferometers achieve ? (Demonstration of the technique) High spectral resolution Polarization capability Bandwidth of up to 4 GHz Angular resolution up to ~0.3 arcsec Detection of molecules up to z=6.42 Open the appetite of (radio-mm) astronomers ! -> ALMA

  9. Let’s take two examples in more details: Plateau de Bure interferometer & SubMillimeter Array

  10. SMA

  11. Frequency coverage PdBISMA 80 – 116 GHz 129 – 174 GHz 201 – 267 GHz 186 – 242 GHz 277 – 371 GHz 272 – 349 GHz 320 – 420 GHz (7 ant, high Tsys) 635 – 690 GHz 1 band at a time Dual frequency operations possible (L/H) + 22 GHz water vapor radiometer

  12. FWHM primary beam -> Mosaicing for extended sources

  13. Configurations / Angular resolution SMA @345 GHz Subcompact: 5’’ extended sources Compact: 2.5’’ Compact NS Southern sources Extended: 0.7’’ (Very extended) Bmax = 508 m PbBI @100 GHz D: 5’’ deep integration CD: 3.5’’ mosaicing BC: 1.7’’ HRA mapping B: 1.2’’ AB: 1’’ A: 0.8’’ very compact sources Bmax = 760 m Summer Winter

  14. LSB 2 GHz USB 2 GHz 10 GHz SMA correlator Very flexible: multiple lines with different spectral resolution (up to 25 kHz, on a limited bandwidth)

  15. 12CO(2-1) IF x 2 = 10 GHz C18O(2-1) 13CO(2-1) Simultaneous multiple lines / isotopes observations with the SMA NGC 4945 USB Amplitude Phase 2 GHz Amplitude LSB Phase

  16. Q1 Q2 Q3 Q4 HOR pola VER pola Dual pola 4 GHz Simultaneous 2 GHz bandwidth PdBI correlator Dual polarization capability 1 GHz bandwidth/unit (2 units possible at the moment) 8 independent spectral units can be allocated: with 20 to 320 MHz bandwidth with 2.5 MHz to 40 kHz channel spacing A new broadband correlator (WIDEX) will be installed this year

  17. Example of correlator setup: multi-line survey

  18. Data reduction / Imaging PdBI GILDAS: CLIC -> MAPPING SMA MIR/IDL -> AIPS, MIRIAD, GILDAS

  19. Tools for proposal preparation - GILDAS/ASTRO - IRAM webpages http://www.iram.fr - SMA Observer Center http://sma1.sma.hawaii.edu -> Tools Beam/sensitivity calculator Calibrator list Passband visualizer

  20. Proposals to PdBI Increasing pressure on observing time Courtesy R. Neri

  21. How to improve the sensitivity ? Example values given for PdBI Courtesy R. Neri

  22. ALMA/ESO Near future Early Science in 2011 More tomorrow

  23. Future of mm interferometry ? Improve the sensitivity: - Large array - Better receivers - Broad bandwidth (continuum sensitivity, line survey) Improve the quality: - Real time phase monitoring (~adaptive optic) Limited fov: - On-the-fly mapping - Multi-beam (pixel) detectors Longer baselines Mm VLBI … another challenge

  24. NOEMA/IRAM Evolution of PdBI -> NOEMA Northern Extended Millimeter Array - Double the number of antennas: 6 -> 12 - Broad bandwidth -> 32 GHz - Extend baselines: 0.8 -> 1.6 km And possible further evolution (better receivers, multi-beam …)

  25. From NOEMA project/IRAM

  26. From NOEMA project/IRAM

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