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)

Keck and Gemini Laser Guide Star Facilities

All-Sky Adaptive Optics is Here!

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

Removing the OH Forest: the final obstacle

Courtesy: Bland-Hawthorn

Fiber Bragg Grating: Created Holographically

Courtesy: Bland-Hawthorn

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

taper transition

Leon-Saval, Birks & JBH (2005),

Optics Letters

JBH et al (2007), Optics Express

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