Magellan 20m Project

Presenters: Wendy Freedman, Carnegie Observatories

Roger Angel, U. Arizona

Steve Shectman, Carnegie Observatories

Matt Johns, Carnegie Observatories

GSMT Science Working Group Presentation

Los Angeles, CA

March 18, 2003

Magellan 20m Introduction & Science

Presenter: Wendy Freedman

Magellan 20-Meter Telescope

[www.ociw.edu/20meter]

GSMT Committee Meeting

March 18, 2003, LAXPresenters: W. Freedman, R. Angel, S. Shectman, M. Johns

Magellans I and II domes

The Magellan 6.5 mTelescopes

CarnegieHarvardSmithsonianMITArizonaMichigan

Las Campanas

The Magellan 20-meter Telescope is…

• Partnership:A consortium of partners currently including Carnegie, Harvard/Smithsonian, University of Arizona, MIT, and the University of Michigan

• Telescope:Roger Angel design conceptSeven 8.4-meter mirrors

• MOU:The partners have committed to funds forthe 18-month conceptual design phase.

• Governing Bodies:Magellan 20 Board: each partner has 2 members. Telescope steering group, Science / Instrumentation plus AO working groups have been established.

The Magellan 20-meter Telescope Planned CharacteristicsMode

FOVFWHM@ 1 µm

Notes

Natural Seeing 15’ 0.4” Gregorian focusmulti-object and high-resolution spectrographs

Single-DM Adaptive 20” 0.007” Natural and Laser guide stars ; HR imaging and near-IR IFU

Ground-layer Adaptive

5’ 0.25” Natural guide stars; HR imaging, deep nearIR multiobjectspectroscopy and low-SB IFU

MCAO* 1.6’ 0.007” Natural and Laser guide stars ; IFUs / high-resolution imaging

20/20 Interferometer*

1’ 0.0017” Requires 2nd telescope and track; direct high resolution imaging of extrasolar planets

* upgrade paths

Science Priorities for the 20m

1. Origin and Evolution of Galaxies and Structure in the Universe

2. The Nature of Dark Matter and Dark Energy

3. Formation and Growth of Black Holes

4. Stellar Populations and Chemical Evolution

5. Origin of Stars and Planets

6. Physical Properties of Extra-solar Planets

Origin and Evolution of Galaxies and Structure in the Universe

Critical issues:1. First light and reionization

2. Assembly of galaxies and clusters

3. Energetics of the IGM

4. Origin of the Hubble SequenceCMB (WMAP image): seeds ofgalaxy and LSS formation

Observational approach:1 High resolution studies of z > 6 QSOs, deep Lyα

surveys in near-IR for first light

2. Sub-L* redshift surveys over large volumes

3. Tomography of IGM using Lyman-break galaxies

4. Dissection of galaxies with natural seeing and AO-fed IFUs in visible and near-IR

Sloan z > 6 quasar

Origin and Evolution of Galaxies and Structure in the Universe (2)

Ly α spectroscopy of high-redshift galaxies:- star forming galaxies at 7 < z < 18:- spectroscopy with IR detectors on M20 - e.g., 10 hours AO near-IR spectrometer- substantially higher sensitivity than JWST

Ly α emission-linespectroscopy

JWST vs M20+AO

Examples:

Galaxy and Structure Evolution:- deep spectroscopic surveys, sub-L* galaxies- 6-10m telescopes insufficient sensitivity- wide-field spectrograph for M20 - reach I~26 [ 0.01 L* at z = 1

0.1 L* at z = 3sfr of 10 M/yr at z = 5]

- hundreds of simultaneous spectra at R~4000Growth of structure in the universe

Origin and Evolution of Galaxies and Structure in the Universe (3)

Examples (continued):

Tomography of the IGM

Baryons in the Universe:- Most baryons in universe in warm IGM- Wide-field multiobject spectrograph- 20m can use galaxies as probes of Ly α

forest instead of sparse QSOs- 5000 objects/sq. deg to AB~24

Galaxy Structure and Formation:- galaxy kinematics and spectral properties - IFU on M20 could extend volume of

universe available for study by 300,000with single-DM adaptive mode

- intrinsic shapes, orbital structures, ages,metallicitiesIFU dissection of nearby galaxies

The Nature of Dark Matter and Dark Energy

Critical issues:1. What is the nature of dark matter?

2. What is the equation of state for the dark energy in the universe? Cluster gravitational arcs

observed with Magellan (BVI)

Observational approach:1. Detailed dynamical studies in DM-dominated

environments (e.g. rich clusters, dSph galaxies)

2. High-redshift SNe studies in the rest-frame visible to test for evolution in SNe properties

Spectroscopy of z ~ 1.5 SNe to confirm down-turn in type Ia Hubble diagram

SNe Ia Hubble diagram

Formation and Growth of Black-Holes

Critical issues:1. Formation epoch for first black holes

2. Growth and feeding of black holes

3. Connection between BH mass and galaxies bulges

Observational approach:1. Near-IR searches for faint first-light AGN

2. Trace evolution of faint-end AGN luminosity function

3. AO-fed spectroscopy of narrow-line regions of low-luminosity AGN to understand accretion modes

4. Velocity dispersions and bulge masses at z ~ 0.3 with AO-fed spectrometers

Black-hole mass measurement

BH mass – bulge mass correlation

Stellar Populations in GalaxiesCritical issues:1. Environmental dependence of IMF

2. Star formation histories in galaxies

3. Chemical enrichment history across Hubble types and masses

4. The first stars: extremely metal-poor stars in the halo of the Galaxy

Observational approach:1. Deep AO imaging in Galactic Center and Local Group

and beyond

2. AO-enhanced near-IR echelle spectroscopy of Local-Group red giants (R~25,0000)

3. Multi-object composite spectra of giants beyond Local Group

4. Super-high SNR (~1000), high resolution spectroscopy of extreme metal poor stars (R~25,000)

Arches cluster in the GC

Leo I color-magnitude

diagram

Simulated SNR = 30 spectra for LG giants

Origins of Stars and Planets

Critical issues:1. What determines stellar, brown-dwarf

and planet mass functions?

2. Environmental influence on planet formation process

3. Evolution from proto-planetary disks to planetary systems

Large segments enable detection of extra-solar planets in reflected light

Radial velocity detection of planets Observational approach:

1. Direct detection of sub-stellar and planetary bodies in near IR from reflected and reprocessed radiation from central star

2. Extend radial-velocity searches to wider range of stellar types

3. Physical studies of debris disks in mid-IR with AO-fed chronographic imagers and spectrometers (key composition diagnostics)

Circumstellar debris disk

Physical Properties of Extra-Solar Planets

Critical issues:1. Physics of planetary atmospheres

2. Survival of “hot Jupiters”

3. What are the distributions of planetary temperature, albedo, mass, size?

Nulling interferometry at 10 µ m with Magellan

Observational approach:1. IR spectroscopy with chronographic and nulling

interferometric imaging spectrometers.

2. Spectroscopic monitoring of transiting systems

M20 direct imaging

M20 nullinginterferometry

Model spectra of giant planets

Magellan 20m Concept & Applications

Presenter: Roger Angel

Magellan 20 telescope•Seven 8.4 m segments•Equivalent diameter 21.5m•18m Focal Length primary•F/10 Gregorian adaptive secondary•Design under study by Magellan team

. Building 57 m diameter by 36 m wide cylinder, 50 m heightTelescope can rotate inside the building when zenith pointing and move in elevation either toward or away from the slit.

Schematic diagram

El axis behind primary vertex

Foci shown are confocal, but can be moved by reshaping primary and secondary figures

G4 focus is folded for vertical axis and flexure-free field rotation

Location of instruments

behind primary

LBT and 20/20 telescope drawn to the same scale

LBT and M20 to same scale (M20 now is a bit bigger, C rings have gone from LBT’s 14 m to 18 m diameter)

CELT Magellan 20

Fast optical design short, 18 m focal length primary

– f/0.7 for 25 m primary envelope – field of view holds up well with fast primary – seeing limited over 12 arcminutes at f/10

Mechanical advantages of fast primary:

Stiff mount, > 5Hz resonant frequency with Davison C-ring mount

secondary wind torque much reduced

Optical advantages of f/0.7 + Gregorian f/10 deformable secondary:

secondary conjugates to ground layer

AO engineering with artificial star at prime focus

M 20 will use large primary segmentsHighly aspheric polishing and support techniques proven for 8.4 m substrates.

Hyperboloidal primary surface made up from seven 8.4 m segments,

-center + ring of 6 identical off axis

-21.5 m effective area

Advantages of large segments:8.4 m, f/1.14 LBT I surface, 24 nm rms

- simple control system

- proven excellent performance (rigidity, thermal equilibration)

- proven accurate wavefront over large areas

- proven support systems allow large scale figure control to 0.1 arcsec

- hexapod positioning for detailed matching to parent surface

M20 segmented deformable secondary

World’s first adaptive secondary at MMT

PSF in H band at MMT, FWHM 0.059, Strehl=40%

Will use deformable secondary technology demonstrated at the MMT

7 secondary segments conjugated to primary segments

8.4 m pri => 0.9 m secondary segment 636 actuators/segment, 4500 in all. Fast go-to, < 1 msec

3 levels of control:

1) fixed shape – seeing-limited

2) ground layer correction – improved seeing

3) AO imaging – diffraction limit

No compromise of either infrared or optical.

Adaptive secondary technology has large stroke (no physical contact of actuators) No need for separate tip/tilt mirror

Diffraction PSF for M20 with AO The secondary support structure is designed to leave completely unobscured the 6 round outer segments. Secondary spider is from upper 9 m hexagonal frame

68% encircled energy in central core (vs 84% for filled circular aperture)

FWHM 18 mas at 2.2 µm

Modeled MCAO realization of PSF, K band, 50” off axis

unique optical features give scientific edge:

Deformable Gregorian secondary with fast primary conjugates to 150 m above telescope – optimally placed for ground layer AO correction (0-300 m) for wide field wide field cover.

Large segments – smooth wavefront and clean diffraction allow direct imaging of known, illuminated exoplanets

Ground layer correction with Gregorian secondary• For fast M20 primary, Gregorian secondary conjugates to short distance above telescope for especially wide corrected field

• Correction limit set by secondary fitting error and tilt anisoplanatism for corrected layer at height z, Strehl S = exp(–6.88(θ(z-z0) /r0)5/3 –( 0.4 Dx/r0)5/3)

For M20, z0 = +150 m (height of secondary conjugate); Dx = 0.3 m (actuator spacing projected to wavefront)

0.680.681.25

Strehl after correction

r0 ground layer(m)

Wavelength (mm)

0.800.951.65

0.390.400.9

Example:

edge of 5 arcmin field (θ=2.5’) layers at ground or 300 m r0 (total) @ 0.5 µm = 0.16 m (0.62 arcsec seeing in V) half total seeing arises in g. layer

Conclusion: ground layer largely corrected over 5 arcmin field in near IR Improvement of ~ 30% in FWHM should be possible, anywhere on skyMethod to be tested with same 0.3 actuator spacing with MMT AO secondary

Example of partial AO correctionMMT adaptive secondary closed at 10 Hz update rate

Useful correction despite large residual error

GCAO modeling in progress (Lloyd-Hart)

Direct detection of known (old) extra-solar giant planets in reflected light with M 20

Planet brightness from stellar illumination ~ inverse square law:

10-5 star at 0.05 AU (51 Peg) to 10-9 star at 5 AU (Jupiter)

For PSF after AO correction, speckle and photon noise in residual starlight should fall off slower than 1/r2, so closest-in planets most favorable for detection

Inner radius limit set by optical imperfections and capability for apodization or nulling to suppress diffraction

Big, clean segments of M 20 enable good suppression for:

1) imaging at ~ 1 AU i.e. ~ 0.1 arcsec

2) spectroscopy at ~ 0.1 AU via interferometric suppression (roasters)

Big segments enable direct detection of

known extra-solar giant planets in habitable zone

5.11.3 × 10-8981.48HD160691-39 º5.4 1.8 × 10-8981.26HD147513

DecV star

Planet/star (J band)

Max. sep. mas

D (AU)

star

Apodized pupil(24% transmission)

-51

º

-51

ºSingle 1 msec frame

� Simulation by J Codona for 20 m telescope, ring of six 8.4 m segments.

� Segments apodized individually for diffraction ~10-6

from 60-120 mas radius in J band (dark annulus).

� AO correction assumes: turbulence moving 10 m/s from left to right. Correction at 1 msec intervals Residual errors yield background 10-5 in annulus

� 4.6 s average shows 10-6 planet at 80 mas, 10-o-clock. 1.4×10-8 planet will require 8 hour integration 4.6 sec, 10-6 planet @ 80 mas, J

AO requirements met by M20 systemM20 design has adaptive secondary with 650 actuators per 8.4 m segment, i.e. spacing ∆x = 30 cm .

For bright stars, wavefront error dominated by spatial fitting.

Strehl S = 1- ∆2 = 1- (0.4∆x/r0)5/3 = 0.91 in J band for r0~ 50 cm

This is higher Strehl than yet achieved, but should be possible given:

* accurate wavefront measurement bright stars * high actuator density * smooth 8.4 m segments. (Magellan II has S = 97% @ 1.25 µm.)

The strength of residual scattered light in the 0.06 – 0.12 arcsec annulus is determined by low order residual errors, of wavelengths ~ 2 m.

These will be measured directly, free from non-common path errors, from the complex amplitude of the focal plane speckles in the annulus (Angel, 2003)

Projected fluxes of a few photons/speckle/msec in J band allow for this

Successive errors will be decorrelated by use of phase tracking algorithm.

Adaptive secondary allows for fast, accurate correction of 2 m scale errors

2. Spectra of giant planets with M20 by interferometric nulling of star

Effective baseline b=13 m, for phase groupings shown. Accurate phase/amplitude servo using (still huge) nulled star signal (few thousand counts/msec)

Tplanet = ¾ sin2(πθb/λ), θ = angular separation

Tstar = ¼ (πab/λ)2, a = star radius

Two domains of interest with planet/star ratio ~ 10-5:

1) bright roasters at 0.05 AU (few mas resolved at ~ 0.9 µm where star suppressed by factor 1000)

2) EGPs at 0.25 AU (~ 20 mas resolved at 3.5 – 5 µm), Ts<.0001

Exposures of several hours should yield spectra with R~ 50 - 500

Nulling interferometry at 10 µm from Magellan, masked as with 2 ellipses (P. Hinz)

Nulling interferometer transmission

Phase sequence for M20 nuller

constructive destructive

Direct detection with Bracewell nulling used to suppress star by factor ≥1000.

Method: Light from the six M20 mirror segments combined interferometrically via single mode fibers, with phases modulated to synthesize a rotating Bracewell nullinginterferometer

Model spectra of giant planets near stars by Sudarsky et al.

Regions accessible with M20 by direct imaging (green) and nulling interferometry (yellow)

Known old giant planets accessible by M20

Star Dec Type Semimajor axis(AU)

sep (mas)

V mag Notes

HD 147513 -39 G5 V 1.26 98 5.4 Direct J imaging

HD 160691 -51 G3 IV-V 1.48 97 5.1 “

HD 1237 -80 G6 V 0.51 29 6.7 Nulling in L band

GJ 86 -51 K1 V 0.117 11 6.2 Nulling in H, K bands

HD 217107 -02 G8 IV 0.072 4 6.2 Nulling at 1 µm

51 Peg +21 G2.5 IVa .052 3.7 5.5“

Tau Boo +17 F6 IV .047 3.4 4.5 “

Upgrade paths

MCAO

20/20

MCAO for M20, design and simulation by Mark Milton and Mike Lloyd-Hart

Uses 10 sodium laser beacons in two pentagons, at 60 and 78 arcsec radius.Nearly complete sky cover at the Galactic pole – needs 18th magnitude tip-tilt NGS on axis.Model used 7 layer atmosphere, integrated r0=0.9m @ 2.2 µm.Correction with adaptive secondary plus 2 additional deformable mirrors conjugated at3.8km and 12.8km respectively, 500 modes each.

At this stage, no time delay or noise in wavefront sensor is modeled, but results include errors from tomographic reconstruction and 500 mode limitation. Frames are for K band, 25 realizations superposed

No correction

With MCAO, on-axis, Strehl=0.79 FWHM=18 mas

With MCAO, 50” off-axis, Strehl=0.49

M20 concept allows for later incorporationinto track-mounted 20/20 pair

When two track-mounted 20 m telescopes combined:

* resolution is increased by 4 times with no loss of point source sensitivity or field of view

* greatly increased thermal sensitivity to exoplanets in Bracewell nulling configuration

The first telescope has no track mount initially, but is made compact and stiff to allow for upgrade

Las Campanas site has room to add track and second telescope later

resolution and sensitivity -single vs double telescope

The reconstructed image from 20/20 will have 4 times the resolution of a single 30 m dish.

Angel has shown that the limiting signal/noise ratio for point sources against sky background is reduced by only 0.3 mag if losses are the same.

In practice, the interferometric combination for the co-moving telescopes of 20/20 requires minimal additional optics, with little loss. 10 σ magnitude limits for 8 h total integration are as follows:

28.128.829.930 m

27.728.529.620/20

KHJband

Note 4 mas resolution for MCAO-corrected K band extends over a 1 arcmin field –richness of Schmidt plate

Simulated 20/20 sensitivity with sky noise by Keith Hege and Laird Close. Stars in galactic bulge of galaxy at 100 mpc

Magellan 20m Instruments

Presenter: Steve Shectman

Instrument Concepts for Magellan 20• Wide-Field Optical Spectrograph

– >10 arcmin, >100 objects

• High-Resolution Optical Spectrograph

– R > 50000

• Near-IR AO Imager

– 10” field, .003” pixels (2K)

• Near-IR AO Integral Field Spectrograph

• Mid-IR AO Imager

• Ground-Layer AO Near-IR Imager

– 10 wavefront sensors, 5’ field, .07” pixels (4K)

• AO Instruments Adaptive Secondary

– Final instrument focal ratios are mild

• Wide-Field Spectrograph Optics, Structure

– Imaging Spectrograph

– Limitations on large optics, mosaic gratings

– Fiber Spectrograph

– Fiber image slicers / IFU’s

– ADC, telecentric corrector

Instruments Telescope

Imaging Spectrograph

• Reflective Optics (Schmidt cameras)

– Small angular field of view

– Compensated by large size (>1m)

– Large mosaics ⇒ high spectral resolution

• Refractive Optics

– Large angular field of view: Match to Gregorian

– Size limitations (0.5m?)

– Moderate spectral resolution

• 13’ dia. field• 36-chip mosaic

• R=4000 at 8500A• 2000A spectral coverage

Fiber SpectrographsTelecentric corrector with ADC ?

• 7 x 0.25” ⇒ 100 micron fibers @ f/3.5

• Charge-Shuffling! 150 mm beam?

• Red Spectrographs

– 4-order echellette, R~5000

– 7 fiber heads per spectrograph (3.5 objects)

– 30 spectrographs

• Blue Spectrographs

– Single order, R~1000

– 35 fiber heads per spectrograph

– 6 spectrographs

Field diameter =

130mm

84.625126

RED: echelletteMarconi CCD42-90:

2048 x 460813.5µm pixels27.6 x 62.2 mm (active)28.2 x 67.3 mm

RGL grating:Blaze: 26.7ºGr/mm: 150R ~ 5050 per 100µm w/ FL 500

o 10,000A (9270-10980, 87mm)o 8560A (8020 - 9270, 73.9mm)o 7490A (7070 – 8423, 64.2mm)o 6660A (6320 – 7070, 56.8 mm)

Magellan 20 Instrument Process• Current work is being done by an ad-hoc telescope

definition group

– To explore impact on telescope design

• Instrument study groups will be formed by SAC

– To develop serious instrument designs

– Detailed consideration of science goals

• Project budget will contain funds for an initial

complement of instruments

– Not necessarily comprehensive

– Instrument competition several years in future

Magellan 20m Project

Presenter: Matt Johns

Baseline Magellan 20m Telescope• 20m – 22m Class telescope

– Composed of six or seven 8.4-m primary mirrors

• Compact telescope structure

• High modal performance

• Reduced mount & enclosure cost

• Staged approach to adaptive optics

– Adaptive Gregorian secondary mirror

• Facility instruments developed as part of the project.

• Upgrade paths for the future.

– Higher-order adaptive optics

– Interferometry e.g. 20/20

• Project follows the successful completion of the Magellan

6.5m telescopes & current developments on LBT.

• Magellan science examples:

HDF

Natural Development Path

6 minute I-band exposure. FHWM = 0.25”

Magellan 6.5m Results

Composite of 400 s

g’, r’, I’ exposures.

Fwhm = 0.35” – 0.40”

These telescopes really perform!

Magellan 6.5m Results

Soft xray transient

XTE J1550-56

I-band

fwhm = 0.30”

MagIC CCD Imager

on

Magellan 1

By Paul Groot

Telescope structures

Experience in building stiff mounts.

Magellan LBT

10 Hz lowest modes 8 Hz lowest modes

• Magellan 20 concept utilizes mirror technology developed on

3.5m, 6.5m, & 8.4m telescope projects

– Monolithic cast mirrors- high figure accuracy & thermal control.

– Capability for producing very fast aspheric optics (M20 f1~0.7)

– Existing production facility is part of the consortium.

Magellan 2

LBT 1

Optics Fabrication

Magellan 20 Mirror Production

• SOML upgrades– New 8-m LOG allowing pipeline processing for mirror generation &

polishing currently being installed.– Assembly area enlargement for staging.– Modify test tower for 18m f.l. off-axis aspheric segments.

• Figuring aspheres– Metrology design & test procedures (Phase A study underway).– CNC control generating & polishing- study (Phase A study)– Technology demonstrator: 1.8m off-axis asphere (Martin/AFOSR)

• Support system revisions for 3-axis operation (Phase A study).

Pacing item: Mirror Production

Mirror production rate- increased staff

Goal:

7 segments

~7.3 years

Projections based on:

• Experience at 3.5m, 6.5m, 8.4m

• SOML upgrades

• 1.8m technology demonstrator

Adaptive OpticsProject takes advantage of institutional AO expertise

-Adaptive secondary mirrors, wavefront sensors, analysis & control

• Strong instrument groups exist at all six institutions.

MIKE Echelle spectrograph

Instrument examples:

OCIWOCIW

Multi-object spectrograph

OCIW

Instrument Development

PANIC IR imager

MagIC CCD Imager MIRAC/BLINC MIR imager/interferometer

HECTOCHELLE

Harvard/MIT

SAO U. Arizona

and more.

• Developed potential sites & infrastructure at LCO.

Magellan (Manqui) Campanas Pk.Alcaino Pk.

La Mollaca Alta(behind)

Campanas PK.

Chilean Sites

Site test data & operations going back well over a decade.

Project Phases

Phase A: Conceptual Development

Phase B: Engineering/Design

– Start of mirror production

Phase C: Construction

Phase D: Commissioning

Schedule

• Science case

• Primary mirror production

• Optical system design

• Telescope structure design

• Optical alignment & phasing

• Adaptive optics *

• Adaptive secondary mirrors *

Phase A Studies

• Primary mirror supports

• Mirror coating *

• Instrument concepts *

• Enclosure studies

• Site survey *

• Operations model

• Cost studies

Active development underway Planned *NSF/GSMT support

Magellan 20m Summary

Presenter: Wendy Freedman

Concluding RemarksThe Magellan 20-meter telescope:• consortium nucleus with expertise in telescopes, instrumentation and

operations; proven success; established infrastructure in Chile

• building on successful technology, incorporating new capabilities enabling powerful gains in sensitivity and angular resolution

• exciting science goals for the baseline design configuration, covering a broad range of topics including the formation and assembly of galaxies, black holes, stars and planets, areas overlapping the GSMT science goals

• the large-segment design is extremely well-suited for detection of close-in planets since big, clean segments enable excellent suppression of diffraction

• we have funding for conceptual design phase; signed MOU to begin fundraising efforts; seeking additional partners

• we represent a significant fraction of the US national astronomy community,AND we have the opportunity to bring in substantial amounts of private money into US astronomy