IAP EpsteinWideField

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Information about IAP EpsteinWideField

Published on November 14, 2007

Author: Willi

Source: authorstream.com

Wide field HAR imaging surveys in the thermal infrared (3-5 µm) from Dome C:  Wide field HAR imaging surveys in the thermal infrared (3-5 µm) from Dome C Nicolas Epchtein CNRS/LUAN/UNSA Main goals :  Main goals Extend 2MASS/DENIS and VISTA/UKDISS Deeper Toward longer l: K dark, L short, L’, M’(NQ) Complete Spitzer; ASTRO-F; WISE Better angular resolution Remove confusion limit (Spitzer/WISE) Imaging Surveys of selected large targets: Magellanic Clouds (global monitoring); Bulge /Disk sample (ISOGAL); Nearby Large Molecular Clouds & SFR (Cham, Carina,..); Deep Fields for extragalactic and cosmology/ nearby very low mass stars Provide astrometric/photometric catalogues to JWST Questions:  Questions science case to extend large scale infrared sky surveys (VISTA-like) beyond 2.3 µm (ARENA 5.1)? Are the future space missions ASTRO-F; WISE; JWST opportunities? Does Dome C provide the appropriate response? If yes, what are the top level requirements ? What is achievable at Dome C within the next decade ? Long range: small ELT (20 m class) dream or reality ? Reflections on an: «Antarctic Mid-Infrared Deep Survey Telescope» (AMIDST) :  Reflections on an: «Antarctic Mid-Infrared Deep Survey Telescope» (AMIDST) General remark:  General remark No High Angular Resolution large scale surveys > K K-L’ index is a simple and efficient test to select dusty objects, in general, much more efficient than IJHK colours K-L index is a powerful tool to evaluate the Mass loss:  K-L index is a powerful tool to evaluate the Mass loss From Le Bertre and Winters, 1999 Slide9:  Classification of Brown dwarfs L and T brown dwarfs K-L’ colours 3-5 µm surveys science impact :  3-5 µm surveys science impact FREE-FLOATING PLANETS IN STAR CLUSTERS and in the field Small bodies of solar system (Kuiper belt) EMBEDDED YOUNG STELLAR OBJECTS EARLY PHASES OF STELLAR EVOLUTION MICROLENSES: OPTICAL AND NEAR-INFRARED COUNTERPARTS New inputs for: ISM (HAR spectro-imaging in 2-5 µm range) THE STELLAR INITIAL MASS FUNCTION THE INTRACLUSTER STELLAR POPULATION THE COSMIC STAR FORMATION RATE YOUNG, MASSIVE STAR CLUSTERS YSOs/ late stellar AGB populations of clusters, MCs, nearby galaxies Cosmological interest (galaxies large z …) window at 4 µm Provide 3-5 µm catalogues for future space missions (JWST) Follow up of WISE improving AR and confusion Slide12:  No deep survey can be carried out from the ground beyond 2.3 µm because of: Sky emission brightness K=12/13 at M. Kea Sky emission instability Instrumental thermal emission (250-300K) BUT from Polar sites Atmospheric emission between 2 et 5.5 µm :  Atmospheric emission between 2 et 5.5 µm Slide14:  in mJy/arsec2 and magnitudes/arcsec2 (approx.) (1) from : Ashley et al. 1996, Nguyen et al. 1996, Phillips et al. 1999, Burton et al., 2001 Sky background measured above South Pole and Mauna Kea Atmospheric transmision between 1.2 et 5.5 µm:  Atmospheric transmision between 1.2 et 5.5 µm Slide17:  From Trinquet et al. 2006 Atmospheric turbulence parameters Focus on the spectral range where Antarctic conditions provide: :  Focus on the spectral range where Antarctic conditions provide: A maximum gain in sensitivity in a relatively poorly explored spectral range Low and stable sky background Low instrumental emission (passive cooling) Excellent atmospheric transmission Large isoplanetic angle and good seeing Low sky and instrumental background:  Low sky and instrumental background Optimized for thermal IR at diffraction limit IT ~ Bl (q/D2) q angular resolution At diffraction limit: IT ~ Bl /D4 point source Extended souces: IT~ Bl /D2 (source size>seeing) Seeing limited  AO depends on isoplanetic angle qo Slide20:  A 3 m AMIDST would be the best 2.3-5.5µm imaging survey facility on the ground Equivalent to a 12 m telescope for extended sources > seeing in the thermal range Wide field (1 –2°)/Switchable SF (DCT concept) Which strategy:  Which strategy IRAIT 80 cm and beyond? PILOT-like 2.5 m class multipurpose Antartized NTT? WF-IR 4 m class telescope (VISTA, DCT)? 8 m class (LSST class) Or even larger? (GMT 7x 8 m) dedicated IR Imaging survey or more general purpose telescope? Spectro-imaging capability A wide field imaging survey dedicated telescope «AMIDST» Antarctic Mid Infrared Deep Survey Telescope:  A wide field imaging survey dedicated telescope «AMIDST» Antarctic Mid Infrared Deep Survey Telescope Objective (requirements): Gain > x10 / Spitzer (IRAC/Glimpse) @ K and L Gain 5 to 10 in angular resolution / Spitzer/WISE FOV > 1° Pixel size ½ diffraction limit at L (3m) 0.3 arcsec optics/coatings optimized at 3-3.8 µm Low emissivity configuration Passive cooling optimized Survey: thousands square degrees in standard mode & a few hundreds in deep mode large FPA covering ~ 1 sq. deg. (16 x 2kx2k) A single dish telescope:  A single dish telescope Wide field 3-meter at Dome C would match the requirements Australian PILOT (2.4m) AO simple (to qo ) off axis primary ?(low emissivity, no diffraction/ High contrast photomery) Passive cooling at 200-220K Day (5+µm) /night (2-5 µm) operations High level of robotisation (remote control telescope & focal equipment) A multi-mirror telescope ?:  A multi-mirror telescope ? 6 dishes of ~ 2-3-8 m f/2 or faster (f/1!) Low emissivity / no secondary diffraction Very compact – easily movable Allows 6 instruments simultaneously on same field!. Possibility of beam recombination – interferometric capability Exemples: LPT concept (NG-CFHT)/ New Planetary Telescope (small version) GMT (Angel et al., 7 dishes of 8 m) IR focal   equipment for AMIDST »:  IR focal   equipment for AMIDST » Multicolour observations IR camera(s) (4 k x 4 k or more) K dark, L s , L’, M’ (e.g., HgCdTe Hawaii 2RG or InSb Aladdin) no « warm» optics cooled dichroïc beamsplitters optimised for each channel Maximum efficiency. FOV 32’ x 32’ or 16’ x 16’ (or more) scale : 0.48 / 0.24 arcsec. (diffraction of a 3 m @ 3.8 µm = 0.65 arcsec ) possibly 10-25 µm camera (SiAs) & even beyond IFTS (1.25-5 µm) Point source sensitivity of a WF survey 3 m telescope at Dome C (diffraction limited):  Point source sensitivity of a WF survey 3 m telescope at Dome C (diffraction limited) Aperture: 3 m FOV = 16’ x 16’; pxl. scale = 0.24’’ ; Thruput = 30% Deep ‘standard’ Survey exposure = 30 s per field 1000 sq. deg. covered in 150 h ( 5 « days ») Very deep survey (Kd et L’) exposure = 30 mn per field 100 sq. deg. covered in some 35 « days » Slide30:  Detection limit (5s)é point source Passively cooled 200K and low background telescope (e = 1%) Hypothesis: diffraction limited, AO; charge capacity : 2.5 105 e- (italics): same telescope at best tropical site (1) Saturated by sky emission in 100ms timeline :  timeline Complete site testing (2005-2008) First experience with IRAIT (2008) Feasibility study of a PILOT like 3m (2007-8) Raise funding thru International sharing of costs (e.g. EC FP7, ESO, Australia + National Agencies+ Polar Institutes) (2007) Working group in ARENA to work out detailed sc. case and optimize TLR (2006-2008)  New infrastructure partly funded by FP7 (2007) Manufacturing: 2009-12 - Mirror 2008-2011 set up on site: summer 2012-13 first light: winter 2014 Concluding Remarks:  Concluding Remarks Dome C: best ground based thermal infrared site 2.3-5 µm is the optimal spectral range for Dome C WF deep HAR imaging surveys:strong science case Little risk. Don’t need further site testing. Start immediately design studies (PILOT ?) Main features: FOV 1° minimum (Prime or RC? Corrector) Aperture  3m minimum Low emissivity and optimal passive cooling Arrays: 1° field + diffraction limit  16 x 2k arrays  4 MUSD first light by 2014 20 m GMT like telescope is « the » OWL telescope

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