current mm interferometers sébastien muller nordic arc onsala space observatory sweden turku summer...
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Current mm interferometers
Sébastien MullerNordic ARCOnsala Space ObservatorySweden
Turku Summer School – June 2009
Current mm interferometers: few facts
- Mm interferometry = Young techniquePdBI: early 90sSMA dedication: 2003
• 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
PdBI milestones
1984 The SMA project (6-elements array) was proposed by the SAO.
1996 The ASIAA joined the project, starting SMART (Submillimeter Array of Taiwan) project.
1999 First two SAO antennas were completed at MKand the first fringe was obtained.
2001 First image was obtained with 3 antennas.
2001 First ASIAA antenna was assembled at MK.
2002 2nd ASIAA antenna was assembled at MK.
2003 The SMA (eight elements) was dedicated.
2004 - Regular science operations
SMA milestones
Current mm interferometers: few facts
- Mm interferometry = Young techniquePdBI: early 90sSMA dedication: 2003
- Few mm interferometers, mostly in the Northern hemisphere
Current mm interferometers: few facts
- Mm interferometry = Young techniquePdBI: early 90sSMA dedication: 2003
- Few mm interferometers, mostly in the Northern hemisphere
- Small array Nant < 15limited instantaneous uv-coverage -> super-
synthesis
- Limited total collecting area
- High altitude site for dry and stable atmosphere
Altitude = 2550mN ant = 6D = 15mArea = 1060 m2
Altitude = 2200mN ant = 15D = 6/10mArea = 772 m2
Altitude = 1340mN ant = 6D = 10mArea = 471 m2
Altitude = 4080mN ant = 8D = 6mArea = 226 m2
Altitude = 5060mN ant = 50D = 12mArea = 5652 m2
(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
What did the current generationof mm interferometers achieve ?
Frequency coverage
PdBI SMA
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 operationspossible (L/H)
+ 22 GHz water vaporradiometer
FWHM primary beam
Freq.(GHz)
SMA PdBI
115 - 42’’
230 52’’ 21’’
345 35’’ 14’’
690 17’’ -
-> Mosaicing for extended sources
Configurations / Angular resolution
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
SMA
@345 GHz
Subcompact: 5’’ extended sources
Compact: 2.5’’
Compact NS Southern sources
Extended: 0.7’’
(Very extended)
Bmax = 508 m
Sum
mer W
inte
r
Very flexible: multiple lines with different spectral resolution (up to 25 kHz, on a limited bandwidth)
SMA correlator
10 GHz10 GHz
LSBLSB2 GHz2 GHz
USBUSB2 GHz2 GHz
13CO(2-1)C18O(2-1)
12CO(2-1)
LSB
NGC 4945
2 GHzIF x 2
= 10 GHz
Phase
Am
plit
ude
Phase
Am
plit
ude
Simultaneous multiple lines / isotopes observations with the SMA
USB
HOR pola
VER pola
Q1 Q2 Q3 Q4
Dual pola
4 GHz
Simultaneous2 GHz bandwidth
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 bandwidthwith 2.5 MHz to 40 kHz channel spacing
PdBI correlator
A new broadbandcorrelator (WIDEX)
will be installed this year
Tools for proposal preparation
- GILDAS/ASTRO
- IRAM webpageshttp://www.iram.fr
- SMA Observer Centerhttp://
sma1.sma.hawaii.edu
-> Tools
Beam/sensitivity calculatorCalibrator listPassband visualizer
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 baselinesMm VLBI … another challenge
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 …)
NOEMA/IRAM