Transcript Overview of the Past Year - Caltech Optical Observatories

The Next-Generation
Adaptive Optics System
at Keck Observatory
Introduction & Overview
Michael Liu & Claire Max
on behalf of the NGAO study group.
NGAO Study Contributors
• Solar System: Franck Marchis (UC Berkeley)
– Maté Adamkovics (UC Berkeley), Antonin Bouchez (Caltech), Josh Emery
(NASA-Ames), Keith Noll (STScI),
• Galactic Astronomy: Michael Liu (Hawaii)
– Andrea Ghez (UCLA), Tom Greene (NASA-Ames), Lynne Hillenbrand
(Caltech), Jessica Lu (UCLA) Bruce Macintosh (LLNL), Stan Metchev
(UCLA), Nevin Weinberg (Caltech)
• Extragalactic Astronomy: Claire Max (UC Santa Cruz)
– Mark Ammons (UCSC), Aaron Barth (UC Irvine), Rich Dekany (Caltech), Don
Gavel (UCSC), David Koo (UCSC), Patrick Jonsson (UCSC), David Law
(Caltech), James Larkin (UCLA), Laura Melling (UCSB), Greg Novak (UCSC),
Tommaso Treu (UCSB), Chuck Steidel (Caltech)
• Technical and Science Instruments: Peter Wizinowich (WMKO)
– Sean Adkins, Brian Bauman, Jim Bell, Antonin Bouchez, Rich Dekany, Ralf
Flicker, Don Gavel, Olivier Lai, David Le Mignant, Bruce Macintosh, Keith
Matthews, Chris Neyman, Viswas Velur
Agenda for today’s presentations
1. NGAO science case: led by AOWG
•
•
•
•
•
•
Introduction & Executive Summary (30 min)
Extragalactic Science (20 min)
Galactic Science: Star & Planet Formation (20 min)
Solar System Science (15 min)
Galactic Science: Galactic Center (10 min)
Summary
2. NGAO technical case: led by WMKO
•
•
•
•
•
•
Introduction & Point Design (15 min)
Performance Budgets (30 min)
Point Design Feasibility and Subsystems (25 min)
Science Instruments (10 min)
Management & Budget plan (20 min)
Summary
Recall the Keck Strategic Plan:
Twenty-year strategic goals for astronomy
• Leadership in high angular resolution astronomy
• Leadership in state of the art instrumentation
• Highly efficient observing
• Complementarity with ELTs
• NGAO addresses all of these!
Keck Next-Generation Adaptive Optics (NGAO)
will provide a powerful new suite of capabilities
1. Near diffraction-limited in the near-IR (K-Strehl >80%)
•
A PSF with unprecedented precision, stability and contrast.
2. Vastly increased sky coverage and multiplexing
•
Enables a much broader range of science programs.
3. AO correction at red optical wavelengths (0.6-1.0 mm)
•
Highest angular resolution of any filled-aperture telescope.
Keck AO has been a tremendous success thus far
Titan
AU Mic debris disk
Galactic Center
Titan
NGS
AO
Kuiper Belt objects
LGS
AO
Merging galaxies
Substellar binaries
Refereed science papers from LGS AO:
Keck has already had a big impact in first 1.5 yrs
Keck
LGS
20052006
Competitive landscape: Other 8-10 meter telescopes are
aggressively pursuing new AO systems.
• Other observatories are focusing on high-contrast
imaging or ground-layer AO
1. High-contrast (Extreme AO): powerful, but highly specialized
– Gemini (GPI, NICI), VLT (SPHERE), Subaru (HiCIAO)
2. Ground-layer AO (“Seeing Improvement”)
– VLT (to feed MUSE and HAWK-I)
– Gemini study
• Only Gemini is pursuing well-corrected wider-field AO
–
Multi-Conjugate AO (~2’ FOV, K-Strehl~0.4)
• Current Keck AO system is ~10 years old.
Keck AO Strategic Plan
• AO strategic plan established by
Keck AO Working Group in Nov
2002, reaffirmed in Sep 2004:
“AOWG vision is that high Strehl,
single-object, AO will be the most
important competitive point for
Keck AO in the next decade.”
• Late 2005: New AOWG tasked by
Observatory and SSC to develop
science case for next-generation
Keck AO.
Overview of this year’s NGAO study
• Solicit broad participation from science & technical
expertise in Keck community
• General approach:
– Analyze a limited set of key science cases, spanning the range of
community interests.
– Develop science requirements for AO and science instruments
– Generate simulations of NGAO performance
– Iterate on science requirements.
– Develop point design.
• 2006 Mar: Science workshop at CfAO/UCSC
• 2006 Apr: Technical retreat in Indian Wells, CA
• 2006 May: Work meeting at SPIE meeting in Orlando, FL
Science requirements for NGAO
• High-level summary of required AO capabilities
Optical
narrow field,
modest Strehl
Near-IR
narrow field,
high Strehl
Thermal-NIR
narrow field,
v.high Strehl
High
Contrast
Wide-Field,
Multi-Object
Solar System
Key
Yes
Yes
Maybe
-
Galactic
Yes
Key
Maybe
Key
-
Extragalactic
Key
Key
-
Yes
Key
NGAO will allow us to tackle many
high impact science areas
1. Near diffraction-limited in the near-IR (Strehl >80%)
•
•
•
Direct detection of planets around low-mass and young stars
Astrometric tests of general relativity in the Galactic Center
Detailed structure/kinematics of high redshift galaxies
2. Vastly increased sky coverage and multiplexing
•
•
Multi-object IFU surveys of GOODS-N, COSMOS, etc.
Resolving the earliest stages of star + planet formation
3. AO correction at red optical wavelengths (0.6-1.0 mm)
•
•
•
Scattered-light studies of debris disks and their planets
Masses and composition of asteroids and Kuiper Belt objects
Kinematic mass determinations for super massive black holes
NGAO Architecture
• Tomography to
measure
wavefronts and
overcome cone
effect
• IR tip-tilt stars,
partially AOcorrected, for
broad sky
coverage
• Closed-loop AO
for narrow fields
• Open-loop AO for
deployable IFUs
90 km
What is Tomography ?
Key performance metrics:
Strehl vs. observing wavelength
Key performance metrics:
Sky coverage and Strehl vastly better with NGAO
• For narrow-field science, Keck NGAO produces high
Strehl ratios over most of the sky in the near-IR.
1
Keck LGS
0.9
NGAO
Sky coverage
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
none
0.050.25
0.250.50
0.500.75
0.750.90
K-band Strehl
all-sky average
r0 = 18 cm,
z=30°
NGAO has dramatically better sensitivity:
Example of near-IR IFU spectroscopy
• Plot shows S/N ratio for
redshifted H, OSIRIS-like IFU:
for 0.6 < z < 2.3, NGAO shows
factor of 3 to 6 improvement
in signal to noise ratio.
• Factor of 9 to 36 shorter
integration times (!)
• If IFU has 6 deployable units,
multiply by another 6x
NGAO + d-IFU has 50-200x
higher throughput than
LGS AO today!
NGAO has dramatically better sensitivity:
Point source sensitivity (1 hour, 5s)
Filter
Current
LGS AO
330 nm WF error
Proposed
NGAO
140 nm WF error
Magnitude
improvement
V
R
27.6
27.1
28.7
29.0
1.1
1.9
I
J
H
K’
26.5
24.4
24.4
24.4
29.0
27.0
25.8
25.2
2.5
2.6
1.4
0.8
L’
Ms
19.2
16.4
19.5
16.6
0.3
0.2
NGAO: Science Instrument Priorities
Single-object
1. Near-IR imager
2. Visible imager
3. Near-IR IFU (OSIRIS?)
4. Visible single-field IFU
5. Thermal near-IR imager
Multi-object
1. Deployable near-IR
multi-object IFU (N~6)
NGAO risk reduction: Key technical elements are
already being tested in the lab and on the sky
• Lasers
– Situation much improved in last few years
• Tomography
– Gemini-South, solar, VLT/MAD, Palomar NGS
• Visible-wavelength AO
– Air Force (demonstrated), Mt. Wilson
(demonstrated), Palomar, Lick
• MEMS deformable mirrors
– Nact=1024 working in UCSC lab, funded by
consortium up through Nact=4096
• Open-loop AO
– Testing now at Lab for Adaptive Optics
– On-sky demonstration coming to Lick
Important linkages between Keck NGAO and TMT
• NFIRAOS: high-order correction, narrow-field MCAO
– Lessons Learned about: IR tip-tilt sensors,sky coverage issues, multiple
laser guide stars, optical design of relay
• IRMOS: multi-object AO system with deployable IFUs
– We envision the Keck NGAO deployable-IFU system to be analogous to
TMT IRMOS, but much less complex
– Half a dozen IFUs instead of 16-20
– More forgiving optical design
– We are benefiting from two excellent TMT feasibility studies for IRMOS
• TMT invested ~$2 M in feasibility studies for NFIRAOS and IRMOS
• In the opposite direction, Keck NGAO experience will help TMT
– Continuing R&D, validation tests
– Earlier implementation on telescope
Uniqueness space for Keck NGAO
• High Strehl in near-IR
• “Precision AO” - both high Strehl and more stable PSF
• AO at optical wavelengths  Takes full advantage of
the unsurpassed aperture size of our 10-m telescope
(and opens a new long-term opportunity for WMKO).
• Deployable AO-corrected IFU instrument
• Takes advantage of world-class AO expertise in the
Keck Community
• Enables a wide variety of new science within the
interests of the Keck Community