wide field har imaging surveys in the thermal infrared (3-5 µm) from dome c

workshop_wide_field_140606 1

Wide field HAR imaging surveys in the thermal infrared (3-5 µm) from

Dome C

Nicolas EpchteinCNRS/LUAN/UNSA


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


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)


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


From Maercker & Burton, 2005, see also Burton et al. PASA 22, 199


Kdark L short

L’

Ks


K-L index is a powerful tool to evaluate the Mass loss

From Le Bertre and Winters, 1999


From Golimowski et al, 2004

Classification of Brown dwarfs

L and T brown dwarfs K-L’ colours


From Cioni et al., ESO Messenger March 2004


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


• 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

From Lawrence et al. (2001)


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


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


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


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


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


• 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• 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

• 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

• 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)


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


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)


High Dynamic range telescope for NG-CFHT

•6 x 8 meter•From Kuhn & Moretto, et al. 2001

Giant Magellan Telescope

7 mirrors 8 m


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)

• 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 »


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


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


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• 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

wide field har imaging surveys in the thermal infrared (3-5 µm) from dome c

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