The James Webb Space Telescope Peter Stockman STScI.

The James Webb Space Telescope

Peter Stockman

STScI

JWST

• Introduction– Architecture overview– Project Status

• Science Capabilities– Optical Performance– Science Instruments

• JWST Science– 4 Science Themes– Ices in YSO disks

• Lab Astro needs• Summary

JWST Observatory : Overview

• 6-m diameter, deployable primary• Provides needed sensitivity

• Diffraction-limited at 2m ~ HST resolution

• 0.6-28 µm wavelength range, near-infrared optimized

• Diffraction-limited imaging and spectroscopy

• L2 orbit• Passive cooling to < 50K

• High observing efficiency

• 5 year mission life (10 year goal)• Cryocooler for MIR instrument

• Station-keeping fuel for 10+ yr

JWST in Ariane 5

Telescope with Labels

Secondary Mirror (SM)

Primary Mirror (PM)Instrumentmodule

SunshieldSpacecraft Bus

Telescope

Cold, space-facing side

Warm, Sun-facing side

L2 Orbit

JWST Status• Prime contractor (Northrop Grumman Space

Technology) – Mirror manufacture underway– Next major review -- PDR & NAR in 2006

• 4 Instruments selected and funded– Long lead time items being fabricated– Most in the process of completing preliminary design

review– Detectors in fabrication

• STScI supporting this effort in preparation for operating the observatory1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017

Concept Development Design, Fabrication, Assembly and Test

mission formulationauthorized

confirmation formission implementation

launch

science operations ...

JWST Full Scale Model

http://www.itt.com/home.asp

Berylium Mirror Segment

Beryllium billet following HIP Beryllium billet following HIP Two blanks ready for machiningTwo blanks ready for machining

Mirror Manufacture

• Brush Wellman uses a Hot Isostatic Press (HIP) process to form the Beryllium mirror billets

• Axsys Technologies machines and etches the beryllium blanks.

Back side light-weightingBack side light-weighting

• Tinsley Laboratories grinds and polishes the mirror segments, at room temperature and after cryo-testing.

JWST Science CapabilitiesOptical Performance (1µm)

Optical Drivers:• Segment Quality (impacts < 2 µm & coronagraphy)• Backplane & collimation stability (impacts photometry & coronagraphy)

Background-limited Sensitivity

• Cameras and R ~ 100 spectroscopy background limited at all wavelengths– 6.5 m mirror >> HST, Spitzer

big gains– Background

• Zodi light dominates at shorter wavelengths

• Thermal emission dominates at > 12 µm

• Other sources– stray light from Galaxy on

dusty mirror, – Earth or Moon shining past

shield onto mirrors

• NIRSpec sensitivity detector limited at R ~ 1000

Instruments

FGS

MIRI

NIRSpec

NIRCam

Replaced by cryo-cooler

NIRCam (U. Arizona & Lockheed Martin)40 Megapixel Camera

• Multiplexing– 2 fields simultaneously– 2’x2’ & 2’x2’– 2 colors simultaneously

• < 2.35 m : 4 x 2048 x 2048

• > 2.35 m: 1 x 2048 x 2048

• 3 functions– Science

• Wide-field imaging

• Coronagraphy

– Calibration– Wavefront Sensing (WFS)

NIRCam Filter Set

Key Component: Detector • HgCdTe IR detectors• Substrate removed to

enable response to 0.6 m

• Long wavelength response at 2.6 m on short wavelength camera, 5 m on long wavelength camera

4 2Kx2K Mosaic in test chamberRockwell Scientific, Camarillo, CA

NIRSpec: ESA & Astrium & NASA

• > 100 Objects Simultaneously• 9 square arcminute FOV

• Implementation:– 3.5’ Large FOV Imaging Spectrograph– 4 x 175 x 384 element Micro-Shutter Array– 2 x 2k x 2k Detector Array– Fixed slits and IFU for backup, contrast– SiC optical bench & optics

QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.

Focal Plane Layout – NIRSpec

• Sensitivity AB 26.2 in R100 at 3 microns in 10000 seconds

• 5.2e-19 ergs/cm**2/s in 10**5 sec at R1000

• Spectral Resolutions (Multi-Shutter Array, Long Slit (0.2” x 4”)Integral Field Unit (3”x3”)– Prism (R~100) 0.6-5 µm

– 6 Gratings (R ~ 1000, 3000) 1.0-5.0 µm

• 750x350 individually addressable shutters

GSFC/NASA

MIRI (European Consortium & NASA)• Cryostat --> Cryocooler (2005)• 2 Si:As BIB 1K x 2K detectors• Imaging (1k x 1k Si:As array)

– 1.9 x 4 arcmin– 5-28 m– R=5 filter set– Coronagraph ( R~10, 25”x25”)

• 10.65, 11.3, 16, and 24 μm

• Spectroscopy – slit spectroscopy

• 5”x0.2” slit• R=100• 5-11 m

– Integral field spectroscopy• R=3000 1000• 3.5x3.5” 7 x 7”• 5-27.5 m

Fine Guidance Sensor (CSA)

• FGS is bore sight guider– Two 2kx2k HgCd

detectors– Acquires pre-planned

guide stars – Centroids guide stars at

20 Hz rate to provide error signals to fast steering mirror

• Tunable Filter Imager– R~100 – 1-2µm & 2-4µm

JWST is driven by 4 Science ThemesScience with the James Webb Space Telescope, Gardner et al (SWG),

PASP in preparation (~ late fall publication)

• JWST General Observer Program (>80% of time)– Annual international peer reviews (like Hubble)– International MOUs (>15% for ESA, 5% for Canadian scientists)

• Requirements determined from 4 science themes– The End of the Dark Age: First Light and Reionization– The Assembly of Galaxies– The Birth of Stars and Proto-Planetary Systems– Planetary Systems and the Origins of Life

• Science Program Demographics (similar to Hubble)– 1000-2000 different targets per year– Equal numbers of galactic and extragalactic targets– Exposure times per target will likely range from 1000 s to 1,000,000 s

(quick Spitzer followups to ultra-deep fields and SNe surveys)

End of the dark ages: first light and reionization

• What are the first galaxies?• When did reionization occur?

– Once or twice?

• What sources caused reionization?

Patchy Absorption

Redshift

Wavelength Wavelength Wavelength

Lyman Forest Absorption

Black Gunn-Peterson trough

z<zi

z~zi z>zi

Neutral IGM

.

• Ultra-Deep NIR survey (1nJy), spectroscopic & Mid-IR confirmation.

• QSO spectra: Ly-a forest

Reionization

• When the IGM is neutral, it is black beyond the Lyman limit at 912 A due to photoelectric absorption

• It is nearly opaque beyond Lyman due to line absorption

• Exiting data suggests reionization complete around z=6.5

• The reionization epoch is unclear– WMAP suggests z~10-20– Most distant QSOs have

significant metals– Ionization history may be

complex

• Wide area photometric surveys for rare high redshift objects with JWST

• SN e Type 1a visible to z~10

White et al 2004

SN II

The assembly of galaxies

• Where and when did the Hubble Sequence form?

• How did the heavy elements form?• Can we test hierarchical formation

and global scaling relations?• What about ULIRGs and AGN?

Galaxies in GOODS Field

• Wide-area imaging survey• R=1000 spectra of 1000s of

galaxies at 1 < z < 6• Targeted observations of ULIRGs

and AGN

Birth of stars and protoplanetary systems

• How do clouds collapse?• What is the low-mass IMF?

• Imaging of molecular clouds• Survey “elephant trunks”• Survey star-forming clusters

Deeply embedded protostar

Agglomeration & planetesimals Mature planetary system

Circumstellar disk

The Eagle Nebula as seen by HST

The Eagle Nebulaas seen in the infrared

High Mass SF – Nature vs. Nurture?

• Low mass star formation thought to be understood– Many rotating cores in MC– Disks forms around central

concentrations– Most of mass is accreted through

disk

• High mass systems may be hard to form this way– Intense light destroys disk and

disrupts system

• Alternative – Nurture– low mass “companions” in

gravitational well of GMC collide to form high mass stars

• MIRI imaging of GMCs should reveal actual populations of young stars

Bonnell et al. 2004

t: 0.66 1.3

1 10 25 many

M 4-8

Planetary systems and the origins of life

• How do planets form?• How are circumstellar disks

like our Solar System?• How are habitable zones

established?

Simulated JWST imageFomalhaut at 24 microns

• Extra-solar giant planets– Coronagraphy

• Spectra of circumstellar disks, comets and KBOs

• Spectra of icy bodies in outer Solar System

Titan

Malfait et al 1998

Spitzer image

Jovian Exoplanet detection with MIRI

• Most Exo-planets to date have been detected by measuring the Doppler wobble of primary star

• JWST/MIRI will attempt to image and in some cases obtain spectra of these directly

atmospheric structure and composition

Spectra – Sudarsky et al 2003

Interstellar Ices Adwin Boogert, California Inst. of

Technology, STScI Colloquium, Feb 2005

–Protostellar disks provide crucial link between evolution of ices from molecular clouds to planetary systems (comets).

–Major difficulty: does line of sight pass through disk and which part of disk? Disk needs to be edge-on.

(Pontoppidan et al. 2005, ApJ, in press) see also www.spitzer.caltech.edu

Direct Observations of Ices in Circumstellar Disks

Solid H2O and CO Vibrational Modes

Gas phase CO: ro-vibrationaltransitions allow J=1, v=1; characteristic P and R branchspectrum.

Solid CO: vibrations only givingbroader absorption whose width, position and shape is determinedby solid state (dipole) interactions.

High resolution required to separate gas and solid bands.At R=3000 JWST NIRSpec andand MIRI can do this.

[ISO satellite observation of Elias 29 in Oph cloud; Boogert, Tielens, Ceccarelli et al. A&A 360, 683, 2000]

Adwin Boogert

Infrared Spectra of Highly Obscured (Proto)Stars

Ice and dust absorption bands observed against continuum of a star or protostarStudy of important species (CO2, CH4,C-H/C-O bending modes in 5-8 m region) severely hindered by atmosphere; use satellites:ISO (1995-1998)Spitzer (2003-now)

background star!

Spitzer Spectroscopy of Ices toward Protostars

/SVS 4-5

Spectra from Spitzer Legacy program “From Molecular Cores to Planet-forming Disks” (c2d)

Adwin Boogert

Ices in Disks

●Direct observations of ices in disks only possible for edge-on disks (obviously).●Difficult, rarely done, and exact ice location often disputed.●Few claims were made (Kastner et al.

1995; Shuping et al. 2000; Boogert et al.

2002; Thi et al. 2002).●Understanding of ices in disks requires

knowledge of disk properties (e.g.

inclination) through mm-wave

observations.

• Prominent band of solid CO detected toward L1489, originating in large, flaring disk.

• CO band consists of 3 components, explained by laboratory simulations as originating from CO in 3 distinct mixtures:

(Boogert, Hogerheijde & Blake, ApJ 568,761, 2002)

Ices in Disk L1489 IRS



– 'polar' H2O:CO





– 'polar' H2O:CO

– 'apolar' CO2:CO or pure CO phase

[NEW!]





– 'polar' H2O:CO

– 'apolar' CO2:CO or pure CO phase

[NEW!]

– 'apolar' pure CO



• Are ices in L1489 IRS disk processed?

Ice Processing in Disk


• Empirical answer by comparing CO ice band with established unprocessed line of sight, NGC 7538 : IRS9:

(Boogert, Blake & Tielens, ApJ 577, 271 (2002))



• Empirical answer by comparing CO ice band with established unprocessed line of sight, NGC 7538 : IRS9:

– apolar CO-rich ices appear to have been evaporated in L1489 IRS disk

– JWST NIRSpec resolution, at R~3000, will be capable of similar studies on many more distant YSOs, simultaneously.

(Boogert, Blake & Tielens, ApJ 577, 271 (2002))


Methane Chemistry

Broad “3.47 m” bandstill unidentified.Tentatively CH/OH stretch vibrations of many species,but so-far only CH3OH, and now CH4 identified.JWST can improve much

•(Boogert et al. 2004)

Suggested areas for Lab Astrophysics for JWST (2003) from Ewine van Dishoeck (pre-Phase A SWG member,

MIRI science team

• Gas-phase transitions– Lowest vibrational transitions: long carbon chains seen toward

post-AGBs– Higher vibrational transitions needed for modeling Exo-Solar

Planetss• Ices

– Higher resolution studies (R~1500-3000) to match JWST resolution

– Better understanding of photoprocessing & ion-bombardment effects

• PAHs– Spectroscopy of large (>30 C atoms) gas-phase PAHs– Reactions and photoprocesses involving PAHs

• Silicates, oxides– Large current effort at measuring spectra and optical constants

Summary

• JWST development is underway• It will be > 100 times more powerful than Spitzer in

the NIR and MIR (5-28µm).• JWST spectral resolution is now capable of

addressing astrophysically important gas and solid phase studies.

• It will join the next generation of observatories (ALMA, Herschel, and SOFIA) in studying the origins of galaxies, stars, and planets.

• Keep tuned to www.stsci.edu/jwst and www.jwst.nasa.gov for news.

http://www.stsci.edu/jwst

http://www.jwst.nasa.gov/

Science Working Group

• Marcia Rieke (U. Ariz.,NIRCam PI)• Peter Jakobsen (ESA, NIRSpec PI), Hans Walter

Rix (NIRSpec Rep.)• George Rieke & Gillian Wright (MIRI PI s)• John Hutchings (CSA, FGS PI)• Matt Mountain (soon STScI, Telescope Scientist)• J. Lunine, Massimo Stiavelli, Heidi Hammel, Mark

McCaughrean, Rogier Windhorst (Interdisciplinary Scientists)

• John Mather, Matt Greenhouse, Jon Gardner (JWST Project Scientists)

• Peter Stockman (STScI)

The James Webb Space Telescope Peter Stockman STScI.

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