Future Giant Telescopes: Evolution in Ground-Space Synergy Richard Ellis Caltech Astrophysics 2020:...
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Transcript of Future Giant Telescopes: Evolution in Ground-Space Synergy Richard Ellis Caltech Astrophysics 2020:...
Future Giant Telescopes: Evolution in Ground-Space Synergy
Richard Ellis Caltech
Astrophysics 2020: STScI, November 13 2007
Ground-Space Synergy (1990-2005)
NASA’s Great Observatories ~$2.5B investment in 8-10m telescopes
Synergistic attributes:
Space: unique wavelengths, angular resolution, reduced IR background, all-sky
Ground: photon-starved spectroscopy, panoramic fields, upgradable technologies
Synergistic SuccessesHDF: HST
GRBs: Chandra/Swift
Some (of many) highlights of this partnership:
• charting the 2 < z < 6 Universe: redshifts, SFRs, morphologies & masses
• origin of various transients: short and long-duration GRBs, X-ray flashes
• physical properties of exoplanets
Transiting exoplanets: Spitzer
"It is impossible to predict the dimensions that reflectors will ultimately attain. Atmospheric disturbances, rather than mechanical or optical difficulties, seem most likely to stand in the way. But perhaps even these, by some process now unknown, may at last be swept aside. If so, the astronomer will secure results far surpassing his present expectations.”
A Vision for Ground-Based Astronomy (1908)
George Ellery Hale, Study of Stellar Evolution, 1908 (p. 242) writing about the future of the 100 inch.
Era of ELTs (2016 - )
A new generation of 20-42m ELTs is being designed:
• Thirty Meter Telescope (www.tmt.org)- Caltech, UC, Canada + poss. Japan- 30m f/1 primary via 492 1.4m segments- $80M design underway (2004-2009)- $760M construction cost (FY2006)- major fund-raising already underway
• Giant Magellan Telescope (www.gmto.org)- Carnegie, Harvard, Arizona, Texas,
Australia + others- 21m f/0.7 primary via 6 8.2m segments - funds for $50M design study being raised
• European ELT (www.eso.org/projects/e-elt)- 42m f/1 primary with 900+ 1.4m
segments - 5 mirror design- 57M Euros design underway
(2007-)
TMT
GMT
E-ELT
How will these AO-designed ELTsaffect ground-space synergy and space astronomy?
JWST vs 8m ground-based telescope
Comparison of 8m JWST and AO-fed 8m ground-based telescope:
Assuming:
• point sources
• AO (projected Strehl of 80% at K)
• Various OH suppression/detector options
Space wins > 2.2 m
Ground wins R>1000 1 < < 2.2m
(1998)
Performance of Keck NGS AO System
50% Strehl
Miranda+Uranus Neptune Titan
R magnituder0 (cm)
Courtesy: Wizinowich & Keck AO team
Performance of Keck LGS AO System
50% Strehl
r0 (cm)R magnitude
NGS
LGS
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
Keck is achieving ACS resolution in K band
Courtesy: Wizinowich & Keck AO team
HST Optical - Keck Near-IR Synergy
Resolved stellar populations in HII regions in IC10
• ACS: I-band
• Keck AO + NIRC2: H, K’ (Strehl ~30%)
• Self-calibration of AO photometry using `curve of growth’ technique (~few % accuracy)
• Combined data enables direct identification of AGB stars, C stars, resolves WR complex
• Analysis reveals multiple bursts of SF & accurate distance
Vacca, Sheehy & Graham Ap J 662, 272 (2007)
Substellar binaries
Refereed Keck AO Science Papers by Year & Type
0.0
2.0
4.0
6.0
8.0
10.0
12.0
14.0
16.0
18.0
20.0
2000 2001 2002 2003 2004 2005 2006 2007
Year
Number of
Solar System
Galactic
Extra-galactic
126 NGS & 30 LGS
Recent Keck AO Highlights
• NGS - seriously limited in sky coverage• LGS - modest Strehl due to `cone effect’• Next Steps:
– Multiple laser to defeat `cone effect’ LTAOLTAO– Multi-DMs widen field with uniform
correction MCAOMCAO– Independent correction of multi-objects in a
larger field MOAOMOAO– Improved seeing over significant fields of
view GLAOGLAO– High contrast planet finders ExAO
Next Generation AO on Existing 8-10m’s
All under active development or implementation
• Tomography overcomes `cone effect’
• AO-corrected, IR tip-tilt improves sky coverage
• Closed-loop for 1st relay; open-loop for deployable IFUs & 2nd relay
Keck Next Generation AO
NGSNGS
LGSLGSNGAONGAO
HCa
Triplet
Courtesy: Wizinowich & Keck AO team
• Hawk-I: 2012 + GLAOHawk-I: 2012 + GLAO– K-band imager, 7.5’ x 7.5’ field
• MUSE visible multi-IFU + GLAO: 2012MUSE visible multi-IFU + GLAO: 2012– 1' field, x 2 seeing improvement
• MUSE visible narrow field IFU: 2012MUSE visible narrow field IFU: 2012– 7.5” field, ~10% Strehl at 750 nm
• SPHERE:SPHERE: 20102010– High Contrast Planet Finder
ESO VLT AO Program
Hawk-I
MUSE
Ground-based 8-10m + NGAO: < < 2.2 m– Masses/composition of KBOs and minor planets:
I-band AO– Debris disks and nearby planets:
high contrast JH, astrometry– Nearby AGN and Galactic center: astrometry,
spatially-resolved spectra at 8500 Å
– Stellar populations in nearby galaxies: imaging– High-redshift galaxies: assembly history etc High-redshift galaxies: assembly history etc multi-
IFU spectroscopy in JHK
JWST: 2013: > 2.2 microns– Very high z sources, stellar masses– Star-forming regions etc
ALMA: 2012ALMA: 2012– Comparable resolution to AO (~ 10-100 mas)– Complementary data on dust & cold gas
Ground-Space Synergy ~ 2015
Resolved Spectroscopy of High Redshift Galaxies
• Major driver for NGAO on 8-10m’s & future ELTs using integral field units (single or multiple)
• Dynamical state, SF - density relations, assembly histories etc
Genzel et al: VLT+Sinfoni Law et al: Keck+LGSAO+OSIRIS
z=2.38 z=2.18
Keck/OSIRIS IFU + LGS (Sept 2007). Keck/OSIRIS IFU + LGS (Sept 2007).
LGS delivers 75mas resolutionLGS delivers 75mas resolution
BUT: x25 magnification so this is effectively ~8 mas in source BUT: x25 magnification so this is effectively ~8 mas in source planeplane
HST/ACS image Keck AO + OSIRIS
Gravitational Lensing + AO : A Preview of the Future
`Cosmic Eye’: a lensed z=3.07 Lyman break galaxy
See http://www.tmt.org/foundation-docs/index.html
Ground-based Synergy (2015-2025): TMT/JWST
TMT and other ELTs will offer the combination of all NGAO gains discussed earlier plus that of increased aperture and resolution
JWST:
- Full sky coverage - 0.6-27 m wavelength range - Superior imaging 1-2.2 m - Stable diffraction limited > 2.2 m - High dynamic range
ELT:
- 25 light grasp - optical sensitivity with 15’ field - 5 better angular resolution - Superior R>3000 1-2.2 m - High spectral resolution capability - Upgradeable
Giant Segmented Mirror Telescope Science Working Group Report
WFE=170 nm (on axis) and < 2 mas image motion at first-light Upgrading to WFE of 120 nm subsequently
23
Laser Guide Star Facility
An extrapolation of existing LGSF architectures, designs, and components– CW solid-state lasers– Launch telescope behind TMT M2– Mirror-based beam transfer optics– Safety and control systems derived from
Gemini LGSFConceptual design review passed in March 2006Laser room sized for physical dimensions of 3 current-generation 50W laser systems to produce 6 25W beacons for NFIRAOSWill monitor future development of advanced components for potential architecture upgrades– Pulsed lasers– Fiber optic beam relays
Resolved Absorption Line Spectroscopy
Peak SB
redshift
HDF-N
Central SB limit for vel. dispersions
Resolved z>1 stellar work is demanding in photons - only possible with TMT!
2 arcmin field ok for clusters, 5 arcmin field necessary for field galaxies
Theorists’ View of Cosmic Reionization
But did it really happen like this..?
Avi Loeb, Scientific American 2006
Probing Early Galaxies: Effect of Source Size
• How small are z~10 sources?
• Strongly-lensed examples have intrinsic sizes ~30mas!
• Gain of TMT+AO over JWST in detection very significant
• Abell 2218 z~5.7 Ly emitter
• Magnification 30
• HST size 0.23 <0.15 arcsec
• Unlensed source is 30 mas
• Source is < 150pc in size!
JWST NIRSpec
TMTredshift
log F (cgs)
TMT/JWST Complementarity
TMT gains in sensitivity, angular & spectral resolution but not field of view
JWST finds luminous sources, TMT scans vicinity to determine topology of ionized shells via fainter emitters - in conjuction with HI surveys
In the era of TMT+JWST we probably won’t be interested in when reionization occurred but rather the physical process as tracked by the topology and structure of ionization bubbles
First device
(Bland-Hawthorn et al 2004)
FBG takes out 96% of OH background by suppressing 18 doublets over 70nm J H
Courtesy: Bland-Hawthorn
Impact of Evolving Synergy
• Current role of space observatories:- unique wavelength range- reduced background- angular resolution
• Angular resolution is increasingly a driver in astronomy
• ELTs + next generation AO will redefine the territory
• Practicality of OH suppression less clear but given sufficient investment could offer great advantages in 0.7 - 2.2 m range
• Unassailable advantages of space (in UVOIR range) - panoramic imaging (AO always ineffective)- optical and UV: very significant opportunities
• JWST does not provide these capabilities
Relevance to Science Themes of Workshop
• Resolved Stellar Populations
• Dark Sector Cosmology:
• First Light and Cosmic Reionization:
• AGN and Black Holes:
• Extrasolar Planets
Some key questions:
• Is there a case for a post-JWST large aperture space telescope?
• Merits of the optical and UV
• Broader role for JDEM given its unique potential