A telescope

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Extragalactic Studies on Galaxy Evolution with a
Wide Field Optical/IR telescope on Dome C

• A telescope
• for an
• ANtarctica
• Imaging
• Survey

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Outline

1. Interesting characteristics of Dome C from an
   astronomer working in the topic of galaxies
2. Definition of the science project and how to
   carry it out
3. Conclusions

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Atmospheric Emission (Burton et al. 2005)
Bands _at_ 200 ?m
Bands _at_ 350, 450 ?m
?
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Thermal Emission at
South Pole and Mauna Kea
? for the same S/NDDome C 3 ? Delsewhere
(ground-based)
Band l ??m) South Pole (1) South Pole (1) Mauna Kea Mauna Kea
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
?SB
3.2
3.2
3.3
3.3

• 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

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Lawrence et al. (2004)

• Exceptional Natural seeing 300 mas above an
  altitude of 30 - 50m
• Wide Isoplanetic Angle 6 arcsecs in
  visible

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Agabi et al. (2006)
Balloon _at_ 30m
2.0 1.5 1.0 0.5 0.0
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Characteristics of Dome C

• Very cold (average -50C down to -90C)
• Very far away
• Dry atmosphere (250 ?m)
• Superb natural seeing (above 30m)
• Wide isoplanetic angles (up to arcmin-sized in
  NIR)
• Long coherence times ( isoplanetic angles ? ?
  NGS)
• Long  nights  ? continuous observations
• High stability (clear skies for 74 of the time
  in winter)

GOOD / BAD

• Very cold (average -50C down to -90C)
• Very far away
• Boreal aurorae (but close to geomagnetic South
  Pole)
• Tough conditions
• Human psychology

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What path for Extragalactic Antarctica Astronomy ?

• Given the known characteristics of Dome C
• Given the known characteristics of galaxies
• Given the (ground-based or space) facilities
  already in use or in (already funded) project
• Assuming that any type of project must be
  (relatively) cheap

Is there a  niche  that would provide
Original Data to (at least) galaxy people ?
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Parameter Spacefor Galaxy Studies
Parameters Range Related Science (not exhaustive)
Field of View 1 arcmin (down to few arcsecs) Individual high-z galaxies
Field of View Few (2-4) arcmins Deep Fields
Field of View Several (10-20) arcmins Local galaxies, small surveys
Field of View ? 1 sq. degree Surveys
Spectral Resolution Imaging (R lt 5) Morphology
Spectral Resolution SEDs (R few 10) SFR, SFH,
Spectral Resolution Low resolution (R few 100) Redshifts
Spectral Resolution Intermediate resolution (R few 1000) Line ratios (Balmer decrement, abundances, )
Spectral Resolution High resolution ( R gt 5000) Dynamics, line profiles
Angular Resolution (in visible) Diffraction limited Stellar populations,
Angular Resolution (in visible) 200 mas Morphology at high z
Angular Resolution (in visible) 1 arcsec Multi-wavelength analysis low-z
Wavelength Range Optical (0.3 - 1.0 um) SFR, SFH, line diagnotiscs
Wavelength Range NIR (1.0 - 2.5 um) Mass, high-z
Wavelength Range MIR (2.5 - 15 um) PAH, AGN / starburst diagnostics
Wavelength Range FIR (15 - 200 um) SFR, dust, AGN/ starburst diagnostics
Wavelength Range Sub-mm (lt 1 mm) SFR, dust
Others cost, PSF stability, temporal resiolution, Strehl ratio / EE, interferometry, coronography, Others cost, PSF stability, temporal resiolution, Strehl ratio / EE, interferometry, coronography, Others cost, PSF stability, temporal resiolution, Strehl ratio / EE, interferometry, coronography,
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What are we left with ?color coding can be
further discussed

• Wide field of view (Ø 1 deg)
• Optical / NIR
• High angular resolution (but not
  diffraction-limited in visible)
• Imaging / SED (/ Spectroscopy)
• Operations the simpler the better

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What do we need ?

• Telescope M1 Ø 3m
• An optical design for a wide field telescope
  providing lt 1/4 PSF ?
• Can we build a telescope on top of a 30-50m tower
  ?
• What if we cant ? Some kind of AO ?

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For instance Optical Design from Gérard
Lemaître

• Dprimary 2 - 3m
• Wide FOV 1 deg2
• 0.3 lt ? (?m) lt 1
• Size of spot 0.25 RMS
• Room for AO ?
• Behavior at ? gt 1?m ?

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How to get rid of the turbulent ground layer ?

• Build some sort of light and stiff 30 to 50m high
  tower ?

h30-50m
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If that proves possible, it is probably the
simple way to reach the specifications but
I recommend not using palm-trees !
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Wider isoplanetic angles

• From Aristidi et al. (2006)
• ?0 (Dome C) 6 arcsec ? 3 x ?0 (Other sites)
  ? x 10 probability of finding NGS in
  visible

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Even wider in NIR

• ?0 (Dome C) 6 arcsecs _at_ 0.5?m
• ?0 (Dome C) 1/2 arcmin _at_ 2.2?m

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GLAOSimulations are being carried out by ONERA
(Thierry Fusco)

• Adaptive optics enable large telescopes to
  provide diffraction limited images, but their
  corrected field is restrained by the angular
  decorrelation of the turbulent wave-fronts.
• However many scientific goals would benefit a
  wide and uniformly corrected field, even with a
  partial correction.
• Ground Layer Adaptive Optics (GLAO) systems are
  supposed to provide such a correction by
  compensating the lower part of the atmosphere
  only.
• Indeed, this layer is in the same time highly
  turbulent and isoplanatic on a rather wide field.

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Point source sensitivity of a WF survey
(borrowed to Nicolas)

• Aperture 3 m
• pixel scale 0.24
• Throughput 30
• Deep standard Survey
• 30 sec per field
• 1000 deg2 in 133h or  5 days 
• Very deep survey (Kd et L)
• 30 min per field
• 100 deg2 in 35 days 

Diff (arc sec) 3m  standard  Survey (?000 sq deg) S/B 5  deep Survey (?00 sq deg.) S/B 5
Kd 0.35 21.8 (17.9) 25.8 (20.1)
L 0.65 16.5 (13.7) 18.7 (15.8)

• Passively cooled 200K and Low background
  telescope (e 1)
• Diffraction limited, AO
• Green italics same telescope at best tropical
  site

NICMOS HDF-N Limiting magnitudes
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Complementary to SWIRE (7 fields 65 deg2)
WISE (All-sky survey)
Antarctica  standard  Survey Antarctica  deep Survey SPITZER (IRAC) (SWIRE) WISE VISTA
Antarctica 3 m Antarctica 3 m space 80 cm space 40 cm Paranal 4 m
Int.time 30s 30 mn 1 sec
Spatial resolution 0.4 (Limited by diffraction at 2 microns) 0.4 (Limited by diffraction at 2 microns) 1.4 5 per pixel 0.7 
Kd 21.8 (17.9) 1.3?Jy 25.8 (20.1) 0.03?Jy n.a. n.a. 19, 21, 22 At K short
L 16.5 (13.7) 62.5?Jy 18.7 (15.8) 8?Jy 19.0 7.3?Jy 15.3 (140?Jy) n.a.

• Green same telescope at best tropical site

NICMOS HDF-N Limiting magnitudes
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OH suppressors studied at OAMP/LAM
(jean-luc.gach_at_oamp.fr for details)

• Sky brightness at 650 nm lt?lt 2.2 µm dominated by
  OH emission will be essentially identical at Dome
  C to that at all other observatory sites,
  including Mauna Kea (Kenyon Storey 2006)
• Decreasing OH airglow -gt increasing SNR (by a
  factor of 2) but also increasing maximum exposure
  times before saturation -gt better efficiency

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Multiband filters studied at OAMP/LAM
(jean-luc.gach_at_oamp.fr for details)

• Lebrun et al. (1998) designed to detect LBGs at z
  3
• Can be also be done in NIR
• Gain in exposure times -gt better efficiency
• No need to frequently change filters

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What would be the  killer  science case of the
Antarctica Imaging Survey (ANIS) ?

• SDSS/VISTA-like survey (several thousands deg2)
• with JWST-like angular resolution (about 0.2)
• from visible to near-infrared wavelengths

• Galaxy Formation Evolution (morphology, SEDs,
  photometric redshifts, )
• Cosmology (cosmic shear, large scale structures,
  )
• Galactic plane (stellar evolution and star
  formation)
• (Extra-)Solar system bodies

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FIR/sub-mm prospective must not be forgotten

• IRAS discovered Ultra Luminous IR Galaxies
  (ULIRG)
• Are there any Ultra Luminous Sub-mm Galaxies
  (ULSG) ?
• First All-Sky survey in the sub-mm range

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Conclusions

• We propose a 2-3m visible - NIR (MIR) telescope
  that includes GLAO, a OH suppressor device and
  multi-band filters to carry out a SDSS/VISTA-like
  survey with JWST angular resolution ANIS
• Must start soon to be useful for JWST, SPICA,
  ALMA
• More to come before Roscoff (hopefully)
• Think about a funding strategy (especially in
  Europe)

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Lets dream
Dome C
Dome C / visible
Dome C / near-IR
Dome C / sub-mm
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M e r c i
Dome C