# Presentation: 532730

## James Webb Space Telescope (JWST) Science Update for AAAC

- James Webb Space Telescope (JWST) Science Update for AAAC

**John Mather**
**JWST Senior Project Scientist**
**NASA/GSFC**
**May 11, 2006**

## Scientific Developments since October 2005

**2006, new WMAP results confirm first results, early first light, predicted redshift for reionization is easier to reach (z ~ 12 vs. 17)**
**2006, planet transits recognized as serious JWST target, including Earthlike planets around M dwarf stars**
**Science Assessment Team recommendations implemented**
- Relax performance < 1.7 microns, etc.
**Scientific Capabilities and Objectives document **
- "James Webb Space Telescope" manuscript accepted for publication in *Space Science Reviews* (J. Gardner, Deputy Senior Project Scientist, and the SWG)
- http://www.jwst.nasa.gov/resources/files/JWST_SSR_JPG.pdf

## JWST Science Objectives versus Cosmic History

**JWST Science Objectives versus Cosmic History**

- Big Bang

- Particle Physics

- Now

- Atoms & Radiation

- First  Galaxies

- Star & Planet Formation

- 380,000 years

- 3 minutes

- 1 billion years

- 13.7 billion years

- 200 million years

- Galaxies Evolve

- Origin of Life & Intelligence

**Study the birth and evolution of galaxies**
- See “First Light Objects”
- Galaxy formation
**Study star and planet formation**
- Coronagraphs will study debris disks and Extrasolar Giant Planets
- Transit spectroscopy of planets

## End of the dark ages: first light and reionization

- What are the first galaxies (beyond those seen by Hubble at z = 6)?
- When did reionization occur?
- Once or twice?
- What sources caused reionization?

- Ultra-deep field
- Spectrum of distant quasars
- Studies of faint galaxies

## The assembly of galaxies

- Where and when did the Hubble Sequence (of galaxy shapes) form? (probably after redshift 6)
- How did the heavy elements form?
- What theories explain the shapes and histories of galaxies?
- What about star-forming galaxies and giant black holes?

- Galaxies in GOODS Field

- Wide-area imaging survey
- Spectroscopy of thousands of galaxies
- Targeted observations of extreme galaxies

## Birth of stars and protoplanetary systems

- How do clouds collapse?
- How does environment affect star formation?
- Vice-versa?
- What is the boundary between low-mass stars and giant planets?

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

- The Eagle Nebula as seen by HST

- Stars in dust disks in Orion (proplyds)

## Planetary systems and the origins of life

- How do planets form?
- Are exosolar systems like our own?
- How are habitable zones established?
- Detection of planets via debris disks
-  Directly image very young planets
- Indirectly detect  planets via their footprints in debris disks

- Exosolar giant planets
- direct imaging by blocking star’s light
- Spectra of organic molecules in  disks, comets and Kuiper belt objects in outer solar system
- Atmospheric composition of exosolar planets
- Observe transits of planets

- Titan

- Visible (HST)

- Spitzer (24 m)

- JWST (20 m)

- Fomalhaut

## JWST characterizes transiting planets

-  Transit light curves
-  Kepler extrasolar giant planets
-  Transit Spectroscopy
-  Terrestrial planets around  M stars
-  Atmospheres of Kepler giant planets

**HST: planet transits star**

**Spitzer: planet passes behind star**

##         Confirmation of Kepler Planet Candidates

**        ****Confirmation of Kepler Planet Candidates**

- Examples of JWST S/N = 35 transit detections
- Earth-sized planet orbiting a sun-like star at 1 AU at Kepler star distances (transit time 13h, d=300 pc)
- Earth-size moon around HD209458b (transit time 3 h, d=47 pc)
- 1. Aperture is key (Det. Lim. regime)
- S/N ~ D2  ~ Collecting Area
-       JWST 25 m2 collecting area
- 	HST 4.5 m2 collecting area
-       (JWST has 6x more)
- 	Spitzer 0.57 m2 (JWST 40x)
- 	Kepler 0.71 m2  (JWST 30x)
- 2. Space is stable
- 	High dynamic range photometry
- 	10-4 – 10-5 possible

- http://www.kepler.arc.nasa.gov/

**1R******** @ 1AU**

**The four sections of a simulated light curve containing the transits of an Earth-size planet (1.0 R****e****) are folded at the correct period, with the sum shown in  red. The presence of the transit is unmistakable.**

- Courtesy: Seager (2005) & Astrobiology and JWST  (contributed by R. Gilliland)

**Notes:**
Notes from Kepler website:

The four sections of a light curve containing the transits of an Earth-size planet (1.0 Re) are folded at the correct period, with the sum shown in red. The presence of the transit is unmistakable.

The figure below shows the sections of the data used in the above simulation. The individual transits are shown (left-hand scale), along with the result of folding and adding the data at the correct period derived with the detection algorithm (right-hand scale).

Text from Astrobiology and JWST (contributed by R. Gilliland)
The two central issues for detecting Earth-sized moons orbiting known giant planets are that of (a) the maximum total number of counts that can be collected per frame with the MIRI/NIRSpec detectors and (b) the cycle time between frames. For example, in the NIRSpec 1-5 micron bandpass, JWST will collect 2 × 108 photons per second from a Sun-like star at 50 pc. If these photons are spread over 104 total pixels on the detector, then integration times must be limited to 0.15 seconds in order to avoid saturation of the pixels at the short-wavelength end of the spectrum. Given a cycle time between successive integrations of 1 second, we can obtain 35-sigma transit detections for the two cases of (1) an Earth-sized moon orbiting HD209458b (transit time 3 hours, d = 47pc), and (2) an Earth-sized planet orbiting the Sun at 1 AU at 300 pc distance (transit time 13 hours). If cycle time is as long as 300 seconds, then the transit detection level for both these cases drops to a less compelling value (in terms of telescope time allocation) of 3-sigma. 

## JWST in Context

- Enormous scientific breakthroughs possible
- Next logical step after HST
- 7x larger collecting area, optimized for infrared that HST can’t see
- Thousands of times faster observations
- Extends science & international partnership
- Builds on Spitzer IR heritage
- 50 x collecting area, much bigger & better detectors
- Angular resolution of HST
- Synergy with planned giant ground-based telescopes
- Essential part of planet program - transits, coronography, dust disks, solar system
- Technology legacy for future missions - detectors, optics, wavefront sensing, adjustment, deployment, coolers

## Summary

- Top priority in astronomy and astrophysics, per National Academy of Sciences and JWST Science Assessment Team
- Revolutionary paradigm-shifting science in 4 major areas:
- First light
- Galaxy formation
- Star and planet formation
- Planetary systems and conditions for life
- Shared facility enables university science
- Provide data to HST and Spitzer users (3600 for HST so far)
- ~ 200 projects each year
- Archive and observing grants planned for ~ $250M in 10 year life
- Risks are well managed
- Cost, schedule, technology, science
- Every reason to expect that public will take ownership of JWST just as with HST

## JWST Science Backup Charts

## Brief History of JWST Science

- 1989 conference, wanted UV telescope much larger than HST
- 1990, HST launched
- 1995, HST & Beyond report, wanted IR telescope > 4 m, optimized for 1-5 microns; project study started; objectives from first light to planets
- 1996, 8 m baselined (50 m2)
- 2002, descoped area by half to 25 m2; accepted by CAA
- 2002, Northrop Grumman selected with 29.7 m2
- 2003, Spitzer Space Telescope launched, showed very early universe bright in IR, observed dust disks around stars, proved need for mid IR on JWST
- 2003, WMAP showed universe lit up very early, redshift ~ 17, moved the goal for the First Light studies to much longer wavelengths
- 2003, JWST descoped to 25 m2, smaller instruments; selected beryllium mirrors
- 2005, deleted tunable filter module, descoped performance at wavelengths < 1.7 microns overlapping with GSMT on ground, relaxed contamination requirements, per Science Assessment Team
- 2006, new WMAP results confirm first results, early first light, redshift easier to reach (z ~ 12)
- 2006, planet transits recognized as major JWST target, including Earthlike planets around M dwarf stars

## JWST Science Assessment Team, 2005

- “The international scientific community is unanimous in regarding the James Webb Space Telescope as the highest priority facility for the US and the international community to advance astrophysical understanding”
- “...the case for the telescope and its unique capabilities has grown in strength and astronomical significance.”
- “JWST is the only facility planned for the next two decades with the resolution and sensitivity in the thermal infrared needed to address the nature of First Light directly.”
- “[JWST]... is positioned to uniquely contribute to the great question: “Throughout the universe, how common are the life generating processes [that] took place almost 4 billion years ago in our solar system?”
- “JWST will therefore be our opportunity to open the window wide to the nature of the fantastically diverse extrasolar planets ...”
- “JWST offers the only IR mission capable of studying extra solar planetary systems this decade”
- Ground-based capabilities are growing at wavelengths  < 1.7 μm with plans for GSMT, so relax performance requirements for JWST where there is overlap