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Wide field HAR imaging surveys in the thermal infrared (3-5 µm) from Dome C. Nicolas Epchtein CNRS/LUAN/UNSA. 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 - PowerPoint PPT Presentation
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workshop_wide_field_140606 1
Wide field HAR imaging surveys in the thermal infrared (3-5 µm) from
Dome C
Nicolas EpchteinCNRS/LUAN/UNSA
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Main goals
• Extend 2MASS/DENIS and VISTA/UKDISS
– Deeper
– Toward longer : 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
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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 ?
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Reflections on an: «Antarctic Mid-Infrared Deep
Survey Telescope»
(AMIDST)
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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
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From Maercker & Burton, 2005, see also Burton et al. PASA 22, 199
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Kdark L short
L’
Ks
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K-L index is a powerful tool to evaluate the Mass loss
From Le Bertre and Winters, 1999
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From Golimowski et al, 2004
Classification of Brown dwarfs
L and T brown dwarfs K-L’ colours
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From Cioni et al., ESO Messenger March 2004
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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
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• 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
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Atmospheric emission between 2 et 5.5 µm
From Lawrence et al. (2001)
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Bande m
South Pole (1)
mJy/arcsec2 mag
Mauna KeamJy/arcsec2 mag
Ks 2.15 0.15 16.5 3 13.4
Kd 2.4 0.3 15.6 6 12.4
L’ 3.8 100 8.6 2000 5.3
M’ 4.8 1000 5.4 2.104 2.1
N 10 2.104 0.8 2.105 -1.7
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
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Atmospheric transmision between 1.2 et 5.5 µm
KHJL’ M’
H20 = 1mm; 1 airmass
KdarkL short
From Storey et al.
250 µm
800 µm
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Site s (arcs) (ms)seeing Isoplanetic angle Coherence time
La Silla 0.9 1.3 1.5
Paranal 0.9 1.9 3.0
Pachon 0.9 2.7 3.0
Maidanak 0.7 2.5 6.6
Mauna Kea 0.8 2.9 2.4
San Pedro 0.7 2 1.2
South Pole 1.9 3.2
Dome C(0) 1.6 5.3 7
H> 30m 0.4 5.3 11.2
From Trinquet et al. 2006
Atmospheric turbulence parameters
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Focus on the spectral range whereAntarctic 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
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Low sky and instrumental background
• Optimized for thermal IR at diffraction limit IT ~ B (/D2) angular resolution
At diffraction limit: IT ~ B /D4 point source
Extended souces: IT~ B /D2 (source sizeseeing)
Seeing limited AO depends on isoplanetic angle o
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• 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)
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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
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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)
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A single dish telescope
• Wide field 3-meter at Dome C would match the requirements – Australian PILOT (2.4m)
– AO simple (
– 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)
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VISTA
A 2-metre optical/infrared telescope for Dome C.
PILOT: Pathfinder for an International Large Optical Telescope.
EOSTImage: Anglo-Australian Observatory
Discovery Channel Telescope (DCT)
Lowell
FOV 2°
4m Flagstaff
Large Synoptic Survey Telescope
8.4-meter
Cerro Pachon
10° FOV
2012
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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)
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High Dynamic range telescope for NG-CFHT
•6 x 8 meter•From Kuhn & Moretto, et al. 2001
Giant Magellan Telescope
7 mirrors 8 m
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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)
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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 »
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AMIDST«standard »
Survey
AMIDST« deep» Survey
SPITZER (IRAC)
(Glimpse)
WISEPxl = 5’’
VISTA
Antarctica 3 m Space 80 cm space 40 cm Paranal 4 m
Int.Time 30s 30 mn 1 sec
K diffract. 0.4’’ 1.4’’ 2.5 ’’ 0.28 ’’
Kd 21.8(17.9)
25.8(20.1)
n.a. n.a. 20.5 (5000°2)21.5 (100°2)
At K short
L’ 16.5(13.7)
18.7(15.8)
15.4 16.6 n.a.
M’ 13.3(10.7 )
14.5 (1)
--15.0 15.9 n.a.
Detection limit (5s)é point source
Passively cooled 200K and low background telescope ( = 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
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0,01
0,001
VISTA
AMIDST std
AMIDST deep
deeply embedded 1 L protostar atdistance 0.6 kpc
T Tauri star at a distance of 0.7 kpc
Ground
Antarctica
Space
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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
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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