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
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
• 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:
– 'polar' H2O:CO
(Boogert, Hogerheijde & Blake, ApJ 568,761, 2002)
Ices in Disk L1489 IRS
• 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:
– 'polar' H2O:CO
– 'apolar' CO2:CO or pure CO phase
[NEW!]
(Boogert, Hogerheijde & Blake, ApJ 568,761, 2002)
Ices in Disk L1489 IRS
• 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:
– 'polar' H2O:CO
– 'apolar' CO2:CO or pure CO phase
[NEW!]
– 'apolar' pure CO
(Boogert, Hogerheijde & Blake, ApJ 568,761, 2002)
Ices in Disk L1489 IRS
• Are ices in L1489 IRS disk processed?
Ice Processing in Disk
• Are ices in L1489 IRS disk processed?
• Empirical answer by comparing CO ice band with established unprocessed line of sight, NGC 7538 : IRS9:
(Boogert, Blake & Tielens, ApJ 577, 271 (2002))
Ice Processing in Disk
• Are ices in L1489 IRS disk processed?
• 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))
Ice Processing in Disk
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.
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)