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The JWST Tunable Filter Imager (TFI)

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The JWST Tunable Filter Imager (TFI) . René Doyon , Université de Montréal, J. Hutchings (HIA), R. Abraham ( UofT ) , L. Albert ( UdeM ), B. Barton (UC Irvine), M . Beaulieu ( UdeM ), P . Chayer ( STScI ), - PowerPoint PPT Presentation
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0-1 The JWST Tunable Filter Imager (TFI) René Doyon, Université de Montréal, J. Hutchings (HIA), R. Abraham (UofT), L. Albert (UdeM), B. Barton (UC Irvine), M. Beaulieu (UdeM), P. Chayer (STScI), L. Ferrarese (HIA), A. Fullerton, (STScI), R. Jayawardhana (U.ofT), D. Johnstone (HIA), D. Lafrenière (UdeM), A. Martel (STScI), M. Meyer (ETH), J. Pipher (U. Rochester), N. Rowlands (COM DEV), M. Sawicki (St-Mary’s), A. Sivaramakrishnan (STScI), K. Volk (STScI) & K. Saad (CSA).
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Page 1: The JWST Tunable Filter Imager (TFI)

0-1

The JWST Tunable Filter Imager (TFI) René Doyon, Université de Montréal,

J. Hutchings (HIA), R. Abraham (UofT), L. Albert (UdeM), B. Barton (UC Irvine), M. Beaulieu (UdeM), P. Chayer (STScI),

L. Ferrarese (HIA), A. Fullerton, (STScI), R. Jayawardhana (U.ofT), D. Johnstone (HIA), D. Lafrenière (UdeM), A. Martel (STScI), M. Meyer (ETH), J. Pipher (U. Rochester), N. Rowlands (COM DEV), M. Sawicki (St-Mary’s), A. Sivaramakrishnan (STScI),

K. Volk (STScI) & K. Saad (CSA).

Page 2: The JWST Tunable Filter Imager (TFI)

TFI at a glance

• FOV: 2.2’x2.2’ • 65 mas pixel sampling• 2048x2048 pixels (Hawaii 2RG)

• Wavelength range: 1.6-2.6 μm and 3.2-4.9 μm• (actually 1.5-2.7 μm and 3.1-5.1 μm)

• Resolving power of ~100 (80-120)• Low-order Fabry-Perot + 8 blocking filters

• Sensitivity, 10σ 10x1000 s• Operating modes

• Normal imaging• Lyot coronagraphy

• 4 occulting spots, 3 lyot masks• Non-Redundant Masking interferometry (NRM)

Wavelengthμm

Sensitivity(nJy) Line flux *

1.5 116 23.32.0 94 14.02.5 73 8.73.5 96 8.24.0 106 7.94.5 129 8.6

×10-19 ergs/s/cm2

Page 3: The JWST Tunable Filter Imager (TFI)

Spectral Resolution

First Light (Z>11.0 LAE)

Exoplanets

Page 4: The JWST Tunable Filter Imager (TFI)

JWST FOV

Page 5: The JWST Tunable Filter Imager (TFI)

TFI Coronagraphy

• 4 occulting spots engraved on the pick-off mirror• Diameters of 0.58”, 0.75”, 1.5” and 2.0”

• 3 lyot masks• Transmissions of 71%, 66% and 21%• Robust against pupil shear up to 4%

• Performance validated in the lab

C71 C66 C21

0.58” and 0.75” 1.5” 1.5” and 2.0”

<1” 1”-2” >2”

Page 6: The JWST Tunable Filter Imager (TFI)

0-6

TFI coronagraph testbed

Beaulieu et al (2008)

Measured Theory

with coronagraph

(observed/theory)

Page 7: The JWST Tunable Filter Imager (TFI)

Multi-Wavelength PSF subtraction(Spectral Differential Imaging)

• Image of the target itself at a different wavelength is used as a reference PSF image.

• Works with either a sharp spectral feature or a flat spectrum.

• Demonstrated in the labwith a prototype etalon + detailed on-orbit simulations.

See poster by P. Ingraham for more details on SDI performance

Page 8: The JWST Tunable Filter Imager (TFI)

TFI contrast limits

For a pupil shear of 2%

Contrast improvement with SDI

Page 9: The JWST Tunable Filter Imager (TFI)

Non Redundant Mask – A unique niche

NIRCam & MIRI contrast from Beichman et al. 2010TFI curve assumes only a modest PSF subtraction performance

goal

Three NRM posters:• Anand Sivaramakrishnan et al• Saavik Ford et al• Barry McKernan et al

Beichman et al 2010

Page 10: The JWST Tunable Filter Imager (TFI)

It’s happening!

Page 11: The JWST Tunable Filter Imager (TFI)

High-Redshift Science with TFI

The Niche for TFI 

• Lyα can be 20x as bright as the continuum for a Lyman Alpha Emitting (LAE) galaxy. • But the Lyα has to escape the neutral IGM! So the ionized region has to be large enough that the expanding Universe redshifts the photon off resonance by the time it hits the neutral IGM. • This means the ionized bubble has to be ~1 Mpc in size. Single sources might not dig out holes this big but one expects sources to be clustered.• Lyα is redshifted into the TFI λ range for z~11-30. • Frustratingly, the regime from z=7 to z=11 is going to be missed… we now know this is likely to be interesting territory. For z<11 the best one can do is chase a Helium line for sources in this range to try to confirm that the source is a Population III object. Iye et al. (2006). Nature 443. 186

Example: LAE galaxy at z=6.96

TFI R=100 BANDPASS

Page 12: The JWST Tunable Filter Imager (TFI)

1 TFI pointing (2.7h)10σ detection at 2.3e-18 ergs/s/cm2.

z=12, IMF=1-100 Msun, Z=1e-3 - - - - z=12, IMF=1-500 Msun, Z=1e-4. . . . . . z=12, IMF=50-500 Msun Z =1e-7

z=12

z=15z=20z=30 4 TFI pointings

16 TFI pointings

Predictions of Lyman Alpha emitting galaxies at z=12,15,30 are highly speculativeCan make a guess by using the parameters (IMF, metallicity, photon escape fraction) defined by population of LAEs at z=6.5 Kashikawa et al (2006)However, THIS IS EXPLORATORY SCIENCE

Can ‘tune’ TFI to redshifts of suspected galaxy overdensities soon to be predicted from high-z 21cm mapping of neutral hydrogen, increasing chances even more.

A single 2.7 hour pointing is sufficient to detect a LAE in the more optimistic, but plausible scenarios. Multiple pointings probe more volume and lead to higher possible detections. Redshifts>12 require lensing or more pointings.

However… the bottom line: we want to go as blue as possible.

Page 13: The JWST Tunable Filter Imager (TFI)

Strategic Considerations

• TFI has a useful niche but the risk of finding nothing with a totally blind search is unacceptably high.

• By 2018 radio observations of redshifted 21cm may inform things so that the odds are much better and searches won’t be blind. But we can’t yet assume that.

• Alternatively, a good strategy would be to come up with a plan that is guaranteed to deliver excellent science with a high-z galaxy search as a by-product.

Page 14: The JWST Tunable Filter Imager (TFI)

A hybrid cluster galaxy assembly + first light campaign

• The concept is a narrow-band imaging survey of galaxies in z~1.3 clusters, with detection of lensed z>11 galaxies occurring if we get lucky. Science goals will focus on the demographics of galaxy assembly in dense environments.

• TFI will be tuned to the systemic velocity of the clusters, isolating the star-forming population from the field population by probing Hα emission.

• TFI’s wavelength coverage is ideal for probing the cluster velocity field (the spectral resolution spans ± 1500 km/s about the cluster’s systemic velocity).

• TFI high spatial resolution will map star-formation structures in individual galaxies as they assemble in the proto-cluster environment.

• TFI’s large FOV is perfect match to the the Einstein radii of rich clusters at high-z, optimizing the probability of detecting strong lensing of background z>11 galaxies. The complex topology of the strong lensing caustic network will be fully sampled.

• The sample will exist by 2018, in fact red sequence + SZ-selected clusters at suitable redshifts are already being found.

• Additional confusion of background high-z systems with foreground cluster members is the price to be paid by this strategy. Efficient removal of false positives will require coordination with ground-based facilities and other JWST instruments.

Page 15: The JWST Tunable Filter Imager (TFI)

Exoplanets

Page 16: The JWST Tunable Filter Imager (TFI)

TFI has unique capabilities

• NRM interferometry• ~10 mag contrast at 70-400 mas• Niche: within IWA of NIRCam/MIRI/TFI coronagraphs (<0.3”)

• High-contrast at ANY wavelength (spectral information)• Niche: spectral characterization of known planets

• Narrow features at >3 μm, high contrast planets

• Spectral differential imaging• 10X attenuation demonstrated• Niche: cool planets (low-mass/old)

• Greater benefit, and works closer in, when sharp spectral features present

Page 17: The JWST Tunable Filter Imager (TFI)

Search for planets in Star-Forming Regions

• Essential to study the primordial stateof planetary systems• After a few 10s of Myr, planetary systems are

expected to have evolved significantly• Insight into formation process

• Direct probe into planetary system evolution• By comparing with older planet populations

• Good test of interior and evolution models• Luminosity function at a few distinct young ages

• SFRs of interest: Taurus [1-2 Myr] and Scorpius-Centaurus [5-15 Myr]• These SFRs are distant (~150 pc) and suffer high extinction (Taurus)

• Need to probe <0.5” (ie <75 AU)• Many stars are faint in optical (I>8), hence cannot be done with ground-based AO

• Relatively untapped by 2018, particularly solar and lower masses

Page 18: The JWST Tunable Filter Imager (TFI)

Planets in Star-Forming Regions – Contrasts

TFI/NRM limit 10 mag 1-2 MJup 75-400 mas 10-60 AU

Page 19: The JWST Tunable Filter Imager (TFI)

• >50% complete for > 2 MJup in 10-70 AU• Can’t be done from the ground or with other JWST instruments

M4M’=11.20.25 M

Detection completeness example – A low-mass star in Upper Scorpius

Page 20: The JWST Tunable Filter Imager (TFI)

GPI/SPHERE/HiCIAO/etc. planets follow-up

• When JWST is launched, GPI and SPHERE will have completed their surveys• Will probe in 0.1”-1” at very

high contrast (10-7:1)• Will detect and characterize

planets at <2.5 μm• Cannot observe at > 2.5 μm

• Expected GPI survey outcome• ~50 planets• Masses 1-10 MJup• a~5-40 AU• Proj. sep. 0.15”-1”

Page 21: The JWST Tunable Filter Imager (TFI)

3.5-5.0 μm contains a significant fraction of total flux

• Follow-up at 3.5-5 μm is important• Atmosphere characterization and luminosity measurement

Cloud free Cloudy

Madhusudhan et al. 2011

Page 22: The JWST Tunable Filter Imager (TFI)

Need TFI/NRM to follow-up GPI planets at 3.5-5 μm

Ground-based NRM limit

TFI NRM limit

Could find new planets here

Page 23: The JWST Tunable Filter Imager (TFI)

Giant planets around low-mass stars

• How often and where do gas giants form around low-mass stars compared to more massive ones?• Not thoroughly addressed by ground-based surveys

(low-mass stars too faint for xAO systems)

• TFI/NRM observations • 50 Myr 0.2 M star at 50 pc• Reaches ΔL’=8 or ΔM=8, at 70-400 mas• Corresponding to 1-3 MJup (L’~M~17-19) at 3-20 AU

• TFI/NRM is the only way to probe same separation for low-mass stars as GPI/SPHERE will probe for more massive stars

• Piggy-back science: molten proto-Earths afterglow

Miller-Ricci et al. 2009

CO2

Page 24: The JWST Tunable Filter Imager (TFI)

Spectral characterization of known planets

• Highest contrast planets at >3.2 μm• Known from ground or found by NIRCam/MIRI

• Planets not doable with NIRCam/NIRSpec in spectroscopy

• Spectral features not covered by NIRCam filters• TFI offers R~90

• Using coronagraphy, spectral differential imaging, roll subtraction, reference star PSF subtraction, etc.

Page 25: The JWST Tunable Filter Imager (TFI)

Some features best characterized with TFI

NIRCam filters

No coronagraphTypical GPI

planet

Page 26: The JWST Tunable Filter Imager (TFI)

Some features best characterized with TFI

NIRCam filters

No coronagraph

Page 27: The JWST Tunable Filter Imager (TFI)

In summary

• Planet search around solar and low-mass stars in young SFRs

• 3.5-5 μm characterization of known, small-separation (<0.3”) GPI/SPHERE/etc. planets

• Planet search at 3-20 AU around young low-mass stars (within coronagraph IWA)

• 3.5 μm characterization of known, wide-separation (>0.3”), high-contrast planets, specific narrow spectral features

Page 28: The JWST Tunable Filter Imager (TFI)

Thank you!


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