The JCMT in the ALMA Era

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The JCMT in the ALMA Era

• Surveying the Sub-millimetre Sky
• (Canada / Netherlands / Great Britain)

Doug Johnstone NRC/HIA
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A New Suite of Instruments

• Faster bolometer array (SCUBA2)
• Continuum mapping at multiple wavelengths
• Ancillary devices (polarimeter, FTS)
• Magnetic fields, line- and SED-fitting
• Heterodyne Receiver Array (HARP-B)
• 16 receivers _at_350 GHz (CO 3-2 etc)
• Submillimetre array (eSMA)

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SCUBA2The Future of Sub-Millimetre Mapping

• gt100 times faster than present instruments
• Survey large regions of the sky quickly
• Square degrees per hour
• Survey to the point-source confusion limit
• Allow for complete source counts
• Finding chart for ALMA
• Beam size 15", centroid to a few arcseconds

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SCUBA2 Key Features

• A large 7x7 arcminute field-of-view
• Fully sampled - Nyquist at 850?m
• Sensitivity governed by the sky background
• Simultaneous imaging at 850?m 450?m
• No chopping required
• Greater sensitivity to
• large-scale structure

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Estimated performance
m
m
Parameter
450
m
850
m
SCUBA
SCUBA-2
SCUBA
SCUBA-2
Per-pixel NEFD
400
75
90
32
Ö
(mJy/
Hz)
Point-source NEFD
400
107
90
22
Ö
(mJy/
Hz)
Point source flux
1
10
1
12
Extraction speed
Large area mapping
1
810
1
980
speed
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Large-scale surveys
SCUBA-2 will map large areas of sky at least 10
times faster than ALMA to the same S/N...
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Deep extragalactic surveys
A 50-hr observation with SCUBA
Deep imaging? It would take SCUBA-2 50 hours to
map 1 deg2 area of sky to the confusion limit
(0.5 mJy) at 850?m
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Wide-field Galactic surveys
SCUBA Galactic Centre Survey
15 shifts (or 120 hrs) of telescope time
Galactic Plane
SCUBA-2 could map the entire area shown left in
just a couple of hours to the same S/N...
Full moon
All sky survey? It would take SCUBA-2 500 hours
to map the entire Mauna Kea sky to the depth of
the SCUBA Galactic Centre image
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Ophiuchus JCMT 2003
In 2003 observed 4 sq. degrees to 40 mJy/bm
as part of the COMPLETE Project. Took 40
hours! Largest SCUBA map to date Expect 100s of
new compact sources
Found only 2!
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Ancillary Instruments

• Polarimeter
• Measure polarized emission and orientation
• Importance of magnetic fields (especially in
  regions of star formation)
• Study the properties of dust
• Fourier Transform Spectrometer
• Moderate-resolution spectrum
• Quickly obtain strong emission lines (e.g. CO)
• Hot core diagnostics
• Low-resolution spectrum
• SED shape - temperature and dust emissivity

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Polarimetry of the Orion Ridge
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When and How?

• SCUBA2 on the telescope by end of 2005
• Full functionality in 2006
• Legacy Surveys being determined NOW!
• Likely 50 of telescope time
• Still time to forward ideas to JCMT members
• Tri-Partate agreement for JCMT expires 2009
• Future of the JCMT beyond 2009 open to ideas
• There will still be a great deal of sky to map!
• Partenership Opportunities

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SCUBA-2 Website http//www.roe.ac.uk/ukatc/projec
ts/scubatwo