the jcmt in the alma era surveying the sub-millimetre sky (canada / netherlands / great britain)...
Post on 05-Jan-2016
217 Views
Preview:
TRANSCRIPT
The JCMT in the ALMA EraSurveying the Sub-millimetre Sky
(Canada / Netherlands / Great Britain)
Doug Johnstone
NRC/HIA
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 @350 GHz (CO 3-2 etc)
• Submillimetre array (eSMA)
SCUBA2The Future of Sub-Millimetre Mapping
• >100 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
SCUBA2 Key Features
• A large 7x7 arcminute field-of-view– Fully sampled - Nyquist at 850m
• Sensitivity governed by the sky background
• Simultaneous imaging at 850m & 450m
• No chopping required – Greater sensitivity to
large-scale structure
~8 arcmin (~100mm)
Focal plane layout
Estimated performance
Parameter 450m SCUBA SCUBA-2
850m SCUBA SCUBA-2
Per-pixel NEFD(mJy/Hz)
400 75 90 32
Point-source NEFD(mJy/Hz)
400 107 90 22
Point source fluxExtraction speed
1 10 1 12
Large area mappingspeed
1 810 1 980
Large-scale surveys
Herschel/SPIRE(350m)25 arcsec : 16 arcmin2
(simulation by Hughes & Gaztanaga)
Compact ALMA(450m)0.01 arcsec : 0.02 arcmin2
JCMT/SCUBA(850m)14 arcsec : 5 arcmin2
(HDF image from Hughes et al. 1998)
JCMT/SCUBA-2(450m)7 arcsec resolution : 64 arcmin2 field-of-view(simulation by Governato et al.)
SCUBA-2 will map large areas of sky at least 10 times faster than ALMA to the same S/N...
Deep extragalactic surveys
SCUBA-2 field-of-view
Hubble Deep Field
Deep imaging? It would take SCUBA-2 ~50 hours to map 1 deg2 area of sky to the confusion limit (0.5 mJy) at 850m
A 50-hrobservationwith SCUBA
Wide-field Galactic surveys
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
~15 shifts (or 120 hrs) of telescope time
SCUBA-2 could map the entire area shown left in just a couple of hours to the same S/N...
Full moon
Galactic Plane
SCUBA Galactic Centre Survey
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 dateExpect 100’s of new compact sources
Found only 2!
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
Polarimetry of the Orion Ridge
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
SCUBA-2 Website: http://www.roe.ac.uk/ukatc/projects/scubatwo
Canadian SCUBA-2
Consortium
top related