MCAO
Brief Overview of the
MCAO Science Case
Francois Rigaut, Jean-René Roy
MCAO
Outline
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High resolution implementation at Gemini
The MCAO Science Workshop
Strawman Instrumentation for MCAO
Excerpt from the MCAO science case:
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Numerical Simulation & analysis results
The IMF in the Milky Way
Stellar populations in nearby galaxies
Distant galaxies: Assembly, Clustering, chemical evolution
• Work to come on Science Case for CDR
May 24-25, 2001
MCAO Preliminary Design Review
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An articulate AO Plan...
MCAO
Gemini North:
• 1999: Hokupa’a 36 (85 upgrade?) on GN
• 2002: The Altair GN facility AO system
• 2003: Laser on Altair increases Sky Coverage
Gemini South:
• 2002: Possibly Hokupa’a south 85 on GS
• 2005: GSAO & LGS available
• 2006: MCAO available
Strong Team. Build or reinforce competence in-house.
May 24-25, 2001
MCAO Preliminary Design Review
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Science with MCAO:
The Santa Cruz Workshop
MCAO
• Following MCAO CoDR + 06/00 GSC, a workshop was organized
to “explore the scientific opportunities for MCAO, quantify its
advantages over current and planned AO systems for a
comprehensive set of science cases and derive the MCAO
instrument requirements”
• Organisation, preparation of science discussions led by P.
Roche (Milky way), B. Schommer/ T. Armandroff/T. Lauer
(nearby galaxies) and S. Morris (distant galaxies).
• Coordination: F. Rigaut/J.-R. Roy
• Modeling work: I. Baldry (AAO), C. Kobulnicky (U.Wisconsin)
and E. Steinbring (CfAO) + GIRMOS studies
• Workshop Oct. 23-25, 2000 at CfAO, UCSC
– About 45 scientists from Gemini community
– Animated and open discussions
May 24-25, 2001
MCAO Preliminary Design Review
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The Science Case Document
MCAO
• Build prior, during and after the MCAO workshop.
• ~ 15 direct contributors + many others
• Contents:
– MCAO in the Gemini instrumentation program
– CAO and MCAO
– I: The global mass distribution of stars -MW
– II: Evolution of galaxies thru stellar pop studies
– III: Evolution of distant field and cluster galaxies
– Appendices
• Science case document reviewed and commented by A.Ghez,
R.Davies, B.Miller, I.Jorgensen
May 24-25, 2001
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MCAO simulations, studies
MCAO
• Design study for MCAO deployable IFUs: sensitivities and
source structures
– I. K. Baldry and K. Taylor
• K band imaging with MCAO
– I. K. Baldry
• A virtual observatory simulator (on line access)
– E. Steinbring
• MCAO distant galaxies science: source density and emission
line fluxes
– H. Kobulnicky, S. Morris, I. Baldry & E. Steinbring
• GIRMOS: Operational Concept Definition Document
– G. Wright & R. Sharples
• GIRMOS development studies
– R. Haynes, I. K. Baldry, K. Taylor, D. Lee, et al.
May 24-25, 2001
MCAO Preliminary Design Review
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Multiplexing advantage and
surface density of targets
Object class
N/arcmin2
Reference
All galaxies (K<20)
10
Broadhurst et al. 1992
HDF Irr (z=0.5-1)
5-6
Fernandez-Soto et al. 1996
Lyman break gals (R<25)
3
Lowenthal et al. 1997
Grav. arcs A2218
10
Kneib et al. 1996
SSCs (B<23) ngc725
10
Schweizer&Seitzer 1998
Orion stars M<0.1 Msun
2
T-Tauri stars
0.1
Proplyds/microjets in Orion
May 24-25, 2001
MCAO
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Haynes et al. 2000
MCAO Preliminary Design Review
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MCAO Strawman Instrumentation
MCAO
Nyquist sampled IMAGER
Band
/D [mas]
Pixel [mas]
FoV (4k2)
J
H
K
32
16
66’’
42
21
87’’
57
29
118’’
• 80” field, 4k2 pix, 20 mas/pixel
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~ 4 million information points
Trade off FoV vs sampling
One plate scale !
Undersampling problems (HST) ?
ISS 2’ Ø hole
and AO fold
May 24-25, 2001
80”x80”
All images credit HST
MCAO Preliminary Design Review
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MCAO Strawman Instrumentation
MCAO
d-IFU / GIRMOS:
• 16-32 units covering the 2’ Ø field
• ~ 0.1” “pixels”, 3” field IFUs
• 1-2.5 m, R~5000
->> Abingdon II
Flamingo II:
• Multi-slit spectrograph
• 2.8 arcmin at F/34 (vs 2 arcmin MCAO FoV)
• Slit width down to 0.1 arcsec
May 24-25, 2001
MCAO Preliminary Design Review
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Actual Anisoplanatism data
MCAO
23”
Typical in H band,
airmass=1.7, r0~ 14cm:
Hokupa’a : 0.12” to 0.19”
-> CAO : 0.042” to 0.153”
May 24-25, 2001
MCAO Preliminary Design Review
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Stellar population: Simulations
MCAO
Generated Stellar fields:
• GC LF
• H-K=0
• Completed down to K=30
15”
• + HB w/ |H-K| <2
• 1/10 GC crowding
• Isoplanatic conditions as
for airmass=1.5
May 24-25, 2001
MCAO Preliminary Design Review
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Stellar populations: Simulations
MCAO
AO
MCAO
Seeing
Seeing 0.65”,
0.6”, field
field40”.
15”.
3600s. Crowded field.
May 24-25, 2001
MCAO Preliminary Design Review
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MCAO
Cut-off on W43 (rich young
cluster in the galactic
plane). Blum et al 1999.
CTIO 0.5-0.8” over 1’2
May 24-25, 2001
Data reduction:
B.Blum, CTIO
MCAO Preliminary Design Review
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The Quest for Astrometry
MCAO
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1 mas/year = 4.5 km/s at 1kpc
Typical V in Globulars, Open clusters = a few km/s
Cluster partnership, mass distribution, ….
No Competition with space mission for sheer
accuracy (a few microarcsec), but (a) large field and
(b) faint objects (8-m!)
• Problem = Systematics. Plate scale ~, static and
dynamic distortions, detector, residual turbulence,
non linearities in DM control.
• Auto-referenced method ?
• Calibration scheme ? Precision and limitations?
May 24-25, 2001
MCAO Preliminary Design Review
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The Science Case Document
MCAO
• I : The global mass distribution of stars -MW
– Probe the bottom of the H-burning sequence and substellar distribution as a function of environment
• II: Evolution of galaxies thru stellar pop studies
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Calibration of the Sne Ia Zeropoint
Stellar pop in nearby Starbursts
Evolution of dIrr vs dE
Intergalactic stars
AGB & RGB tip in Virgo/Fornax clusters
Extragalactic Globular Clusters
• III: Evolution of distant field and cluster galaxies
– Internal galaxies characteristics: Kinematics /
metallicity/extinction/SFR. Field and Clusters.
– Lensed galaxies, galaxy clusters
May 24-25, 2001
MCAO Preliminary Design Review
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Star formation and the Initial
Mass Function in the Milky Way
P. Roche, M. Meyer, H. Richer, P. McGregor, B. Brandl, P. Puxley,
D. Simons, D. Crabtree and J.-R. Roy
• Low end of the IMF: evolution w/ environment as a
tool to investigate star formation processes
– determine IMF for a variety of conditions:
densities, metallicities, ages
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Orion and other star forming regions: Densities
Open Clusters: Ages
Globular Clusters: Metallicities
Young Stellar Super-Clusters: Densities, low to
high mass ratio
IMF as a function of cosmical
time and environment
MCAO
• Orion - imaging
– M, L distribution of stars at
bottom of H-burning sequence
– Explore fragmentation limit
• In Orion, 1 mJ in 1hr at H
• Orion - spectroscopy
– Surface gravity (M/R) and Teff
– Proper stellar atmosphere
analysis
• Astrometry: 0.5 mas/yr per
km/s
– Membership and masses from
binaries
May 24-25, 2001
MCAO Preliminary Design Review
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Young super stellar clusters:
30 Dor, NGC 3603, ...
MCAO
IMF: Probe high mass down
to brown dwarfs
• 0.4 Msun, 1 Myr  K=21.5
– Beat confusion: PSF of
MCAO
• Spectroscopy
– Age, mass
– IFU privileged sampling
aperture
May 24-25, 2001
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Instrument requirements
Star Cluster Studies
MCAO
• Imaging
– Largest field as possible (~80 arcsec)
• Edges more difficult for astrometry
– Special readout time to avoid saturation of brightest
stars
– Spatial resolution
• Nyquist sampled at H
• Better understanding of crowding
– Faint stars vs background and foreground objects
• Trade-off between sampling and field
• Spectroscopy (FLAMINGOS 2 is fine)
– Slitlets for Orion: ~200 objects over 5x5 arcmin2
– Dl = 0.1 mm per pointing; R = 4000 prefered
May 24-25, 2001
MCAO Preliminary Design Review
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Nearby Galaxies
MCAO
• Contributors: B.Schommer, B.Brandl, G. da Costa,
T.Davidge, R.Doyon, T.von Hippel, J.R.Roy, ...
• General goal: investigates star formation in a
variety of environment:
– Starburst galaxies
– dIrr vs d Ellipticals
– Nearby galaxy spheroids
– Extragalactic globular clusters
May 24-25, 2001
MCAO Preliminary Design Review
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Distant Galaxies
MCAO
• Contributors: S.Morris, M.Edmunds, I.Jorgensen,
C.Kobulnicki, D.Koo, D.Schade, R.Sharples, T.StorchiBergmann, H.Yee, ...
• Galaxy formation and evolution:
– Mass assembly of galaxies
– When did the bulk of star formation occurred ?
– History of galaxy clustering
• Proposed programs:
– Evolution of field galaxies:
• Imaging: Morphology
• Chemical evolution: metallicity/luminosity/linewidth
– Galaxy formation: Mass of galaxies at z=2
– Galaxy formation in cluster
– Gravitational lensing
May 24-25, 2001
MCAO Preliminary Design Review
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MCAO
Emission lines in high z galaxies
The aim of MCAO spectro
-measure key diagnostic
nebular lines to derive
o velocities
o extinction (Balmer dec)
o abundances
o SFR
-explore ~/> 10 objects per
MCAO fields
-sample each object  IFU
> 10 points for gradients
> 40 points for “breaks”
May 24-25, 2001
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Gravitational lensing studies of
high z galaxies (Edmunds & Sharples)
MCAO
• Exploit amplification
– Spatial abundances distribution
– Resolved kinematics to study gas
flows and masses
• Constrain inportance of early
strong flows and outflows
• Why?
– Natural scale for strong lensing
(~0.25 Mpc) well-matched to
MCAO fov
• Majority of lensed bkg
galaxies lie at z = 1 – 2
• “gradient “ in z from center
outward
May 24-25, 2001
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Formation of bulges/disks at
z=0.6 – 1.4 (H.Yee)
MCAO
• Understanding cluster
growth/richness distribution of
galaxy types
– Variation of galaxy masses
• As as function of z
• As function of radial distance
within cluster
• Compare mean bulges and disks
to field
• Strategy
– Imaging 10 clusters with MCAO and
HST/ACS
– Non AO imaging with GMOS and
FLAMINGOS
– MCAO spectroscopy at Ha to get
rotation curves
May 24-25, 2001
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The masses of galaxies at z=2
MCAO
S. Morris et al.
• Understanding assembly of
building blocks of galaxies at z =
1.3 – 2.7
– Rotation curves from emission
lines; R ~ 3000-5000
– MCAO multiplexing (12)
• Strong drive for 2’ field
• But 1.5-2.0” IFU suffice
– Serendipity spectro of Ly a
galaxies (1 per sq. arcmin at z=4.5)
May 24-25, 2001
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…masses of galaxies: z=0.5-2
MCAO
• Needed spectra = IFUs (~16)
– Measurements of Ha disk rotation (50 km/s) to 1 scale length
(6 kpc: 0.’’75 at z=1)
– [OII]+[OIII]/Hb or [NII]/[OIII]  12+log O/H
• Statistical sample requires multiplex gain
– Surface density ~10 arcmin-2
– 3 bins of morphology, luminosity, environment and redshift
• 10 objects per bin; >800 galaxies  30 nights
May 24-25, 2001
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MCAO
MCAO Science Case
The next steps
MCAO
From Jupiters to giant clusters
May 24-25, 2001
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MCAO
Imaging and spectroscopy with MCAO
• Imaging science cases: most convincing
– Proof of astrometry to 2 mas/yr will greatly
strenghten the science case of MCAO imaging
over ~1 arcmin field
• Spectroscopy with MCAO
– Multi-slitlets: FLAMINGOS-2 fed by MCAO
could fulfill many key science objectives
– Multi-deployable IFUs: most desirable for
distant galaxies and SSCs in nearby galaxies
• Photon starved spectra
May 24-25, 2001
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MCAO
Exploring very distant galaxies (z>3)
Our knowledge of high z galaxies is rest frame UV based.
Probing the rest frame optical window is crucial:
- Balmer Luminosities: SFR, extinction
o compare SFR(Ha) vs SFR(UV)
- 12 + log O/H abundances
- Integrated widths of lines= velocity dispersion  Mass
Prominent HII region lines shifted to Near-IR, but need right match of z
May 24-25, 2001
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MCAO
LBG NIR spectra
• Typically 2-hr exp.
Times on Keck/NIRSEC
or VLT/ISAAC
• R ~ 1500
• Spectra dominated by
strong nebular lines
– Little continuum
• Out of 15 galaxies, only
4 objects with
sufficient S/N
Keck/NIRSPEC
May 24-25, 2001
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Spatially resolved emission
MCAO
ISAAC spectrum:
[OIII] 5007, 18000s
FWHM = 0.62 arcsec (4.7 kpc)
May 24-25, 2001
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MCAO
1’’ slit
MCAO view of z=3 galaxies will be no better than HST !
May 24-25, 2001
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Multiplexing requirements
MCAO
• To extablish a radial behavior + a central value
– Monotonic gradient: 12 points with S/N > 5
– Gradient with single break (rotation curve or abundance
gradient in a young barred galaxies) : ~ 48 points with
S/N > 5
– Gradient with two breaks : ~ 160 points with S/N > 5
• Recent spectroscopy of galaxies at z ~ 3 from
Keck/VLT (e.g. Pettini et al. 2001) shows that it is
extremely challenging
– However, similar studies at z=1 are feasible
May 24-25, 2001
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MCAO
Spectroscopy of distant galaxies (z>3)
• Recording all the lines in JHK with adequate R and
S/N  one full night on 8-10 m
• Even with IR MOS, assembling a sizeable sample of
high z galaxies  major observational effort.
– Getting robust physical parameters (O/H, rotation
curves) will require 30-50m
May 24-25, 2001
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…A living document:
“final” version for CDR
MCAO
• Develop simulation to strenghten the case
for astrometry at the mas/yr level
– Brent and Francois to explore further
– Consult astrometrists
• MCAO spectroscopy
– FLAMINGOS-2 capability at fulfilling near term
goals: Michael Meyer (Steward), Brian Miller
(Gemini)
May 24-25, 2001
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Steps toward the final version of
the MCAO Science Case
MCAO
• Establish for several science cases real
fields
– Put together potential MCAO fields, observing
schedule/timing (satellite interference),
availability of tip/tilt stars
– Predict full field (JHK) performances and
generate images/spectra
• Deadlines for “final” MCAO science case
– GSC meeting of July 2001 and Board meeting of
November 2001 (updated from PDR input)
– CDR in late 2002
May 24-25, 2001
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MCAO
Conclusions
• Santa Cruz Workshop triggered strong interest for
MCAO across the Gemini partnership
– Provided backbone to current science case
– Defined several MCAO imaging cases
– FLAMINGOS-2 will cover most (but not all) spectroscopy
programs
• GIRMOS to be re-visited during Abingdon II
• Community endorsement of MCAO+Near IR imager
• Some of the science cases require a 30-50m
telescope with MCAO
• Feasibility and more quantitive work to be completed
for CDR
May 24-25, 2001
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MCAO
PDR Agenda
Thursday, 5/24
0800 Welcome
0805 Project overview
0830 Science case
0930 Break
0945 System overview
1015 System modeling
1100 AO Module optics
1145 Lunch
May 24-25, 2001
1245 AO Module mechanics
1340 AO Module electronics
1400 Break
1415 Beam Transfer Optics
1510 Laser Launch Telescope
1545 Closed committee session
1800 Adjourn
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