Dome C: An Antarctic Submillimetre Observatory - Unlocking Unique THz Windows

1. ALMA-type antenna potential for submm astronomy at Dome C: An Antarctic Submillimetre Observatory Vincent Minier - CEA Saclay/France Luca Olmi - INAF/Italy & UPR Nick Tothill - Exteter/UK and a growing ARENA submm team 75° 06' S - 123° 20' E - 3233 m

2. Unique THz windows 450 µm 350 µm Chajnantor/ALMA Dome C ~200 µm opens ! Credit: N. Schneider

3. Unique THz windows

4. Unique THz windows • PWV < 0.5 mm at Dome C (TBC) • 25-50% winter time PWV~0.2 mm (<10% at Chajnantor)  200 µm opens • 350/450 µm open 90% winter time + fraction of daytime (30-40% at Chajnantor) • High stability & low skynoise expected at Dome C (10-50 times lower than at Chaj.)

5. Unique THz windows • Mapping time: (NEFD/Flux)2 x 1/FOV  (NEP/De-)2/Flux2/2 • Map. time (12m) = 4 x Map. time (25m) at a given  and . • But PWV percentile and skynoise at 350 µm could compensate x4  over a yr, same amount of observations done. • 12 m@200 µm offers the same angular resolution as 25m@450 µm.

6. Unique Science • Planetary disk histories • Star formation in the Galaxies and beyond (Chamaleon, Carina, LMC, starburst galaxies) • Galaxy formation and evolution (CIB, census of star formation & AGN role) • CMB - SZ below 2 mm (cluster of high-z galaxies) • Transverse: Molecular spectroscopy (NII, CO…)

7. Unique Science Tdust=40 K 20 K Luminosity Temperature Mass 200-450 µm IMF Class 0-like high-mass protostar

8. Hubble Deep Field 3’ SCUBA 850m Hughes et al. 1998 Unique Science z=3 z=5

9. Unique Science • Star formation @200 µm: res.=0.1 pc, 1 deg2 in a few days, sens.: 0.1 M (10 ) @ 5 kpc • CIB@350µm: 2.5 mJy (5-) over 1.3 deg2 in 3600 hrs  2 winters

10. Unique pathfinder • A 12m telescope for preparing future and larger facilities • A >25m telescope (great for CIB) but wind, pointing and T° gradient issues at 200 µm • A THz+mid-IR telescope (Olmi’s ASO) but mid-IR upgrade will delay the project • 3 x 12m interferometer with short spacing • ‘Simulate’ a 25m telescope • THz heterodyne (ALMA will not do it) • Bolometric interferometry to prepare FIRI space mission in the framework of ESA Cosmic Vision ?

11. Unique pathfinder • Use ALMA design (Thales or Vertex) • As cheap (~10 M€) as designing a 5m antenna (?) • Much cheaper than the cost of a 25m tel. (100 M€) • Can do very good science by 2014 • Limited surface accuracy upgrade to a minimum (?)  design study on thermal effects (gradient and ~-70°C temperature) • Prepare polar engineering to larger facility, e.g. an interferometer.

12. Conclusions • Why a 12m submm telescope at Dome C ? • Unique THz windows • Could perform Unique Science at 200-450 µm • Unique opportunity and pathfinder • Happening now and to be done (roadmap): • Design study by industries • Environmental studies (GIVRE, wind…) for engineering • 200 µm transmission & PWV to be measured (2008, 2009) • Skynoise at Dome C to be estimated and measured (CAMISTIC on a small telescope).

13. Why a 12m submm telescope at Dome C ? • Unique THz windows • Could perform Unique Science at 200-450 µm • Unique opportunity (2014- ~10 M€) and pathfinder to larger facility: Numbers of 350um (>5sigma) sources expected in a 10 arcmin^2 field with a 3.1’x3.1’ bolometer array; mostly high-z (z>1) sources, based on LeBorgne et al 2007 counts to 10mJy (plausible Herschel confusion limit): 8/field (requires ~ 1 hour with a 12m telescope) Lbol ~ 2x10^12 @z=2 to 1mJy (~ confusion limit with 6.2” resolution): 110/field (requires ~ 100 hours with a 12m telescope) Lbol~1.7x10^11 @z=2 to 0.3 mJy: 200/field (50 hours with a 25m telescope) Lbol~4x10^10 @z=2 (from E. Daddi) • Great science case for a 3 x 12 m antenna interferometer • Happening now and to be done (roadmap): • Design study by industries • Environmental studies (GIVRE, wind…) for engineering • 200 µm transmission & PWV to be measured (2008, 2009) • Skynoise at Dome C to be estimated and measured (CAMISTIC on a small telescope - 2010).