NIRISS René Doyon, Université De Montréal, FGS/NIRISS PI

Transit Spectroscopy with NIRISS René Doyon, Université de Montréal, FGS/NIRISS PI

ExoPAG 9 4 Jan 2014 1 Collaborators

• David Lafrenière, UdeM (NIRISS exoplanet team lead) • Loic Abert, UdeM • Etienne Artigau, UdeM • Mike Meyer, ETH, Switzerland • Ray Jayawardhana, Toronto • ….

ExoPAG 9 4 Jan 2014 2 Outline

• NIRISS overview • Transit spectroscopy capability • Simulations • Performance limitations

ExoPAG 9 4 Jan 2014 3 FGS/NIRISS overview

• Two instruments in one box provided by CSA • FGS (Fine Guidance Sensor) • Provides fine guiding to the observatory • 0.6-5 µm IR camera. No filters, single optical train with two redundant detectors each with a FOV of 2.3’x2.3’ • Noise equivalent angle (one axis): 3.5 milliarcsec

• 95% sky coverage down to JAB=19.5 • NIRISS (Near-Infrared Imager and Slitless Spectrograph) • 0.7-5 µm IR camera. • Four observing modes • Main science drivers • First Light: high-z galaxies • Exoplanet detection and characterization

ExoPAG 9 4 Jan 2014 ExoPAG 9 4 Jan 2014 5 ExoPAG 9 4 Jan 2014 6 ExoPAG 9 4 Jan 2014 7 NIRISS SOSS (Single-Object Slitless Spectroscopy) mode

• Specifically optimized for transit spectroscopy • Unique features • Broad simultaneous wavelength range: 0.7-2.5 um • Built-in weak lens to increase dynamic range and minimize systematic ‘’red noise’’ due to undersampling and flatfield errors. • Key component is a directly ruled ZnSe grism (manufactured by Bach) combined with a ZnS prism, all AR coated except the ruled surface on the ZnSe grism. • Two spares were manufactured by LLNL and received October 2012 (after instrument delivery in July 2012) • Groove quality much better/sharper compared to the flight grism. Measurements and model suggested improved efficiency by > 2x. • Plan is to swap grism after CV2.

ExoPAG 9 4 Jan 2014 8 SOSS mode implementation

Monochromatic PSF measured in the lab

20 pixels

ExoPAG 9 4 Jan 2014 Blaze function – Flight vs Spare

~2x

~4x

ExoPAG 9 4 Jan 2014 10 Total throughput – NIRISS vs NIRSpec

NIRSpec A1600/PRISM/CLEAR 0.30

0.25 NIRSpec MOS1x3/G140H/F070LP NIRSpec A1600/G140H/F070LP R=30-90 R=1300-3600 NIRISS Spare (LLNL) 0.20

R=430-1350 0.15 Throughput NIRISS Flight (Bach) 0.10 Kaltenegger & Traub (2009

0.05

0.00 600 800 1000 1200 1400 1600 1800 2000 2200 2400 2600 Wavelength (nm)

Curves include a conservative margin (~20%)

ExoPAG 9 4 Jan 2014 11 Total throughput – NIRISS vs NIRSpec

NIRSpec A1600/PRISM/CLEAR 0.30

0.25 NIRSpec MOS1x3/G140H/F070LP NIRSpec A1600/G140H/F070LP R=30-90 R=1300-3600 NIRISS Spare (LLNL) 0.20

R=430-1350 0.15 Throughput NIRISS Flight (Bach) 0.10 Kaltenegger & Traub (2009

0.05

0.00 600 800 1000 1200 1400 1600 1800 2000 2200 2400 2600 Wavelength (nm)

Curves include a conservative margin (~20%)

ExoPAG 9 4 Jan 2014 12 Saturatiom limits – NIRISS & NIRSPec

4 Unsaturated m=2, partial saturation in m=1 55 Cnc e (256-pixel sub-arrray) 0.9-2.5 μm , m=1 only 6 HD 189733 b (80-pixel sub-array) HD 209458 b 0.7-2.5 μm , m=1, m=2 GJ 436 b (256-pixel sub-array)

8 Educated guess of M dwarfs yield from TESS. GJ 1214 b 10 CoRoT-7 b J-band magnitude

12 Assumes 4-amp read-out mode or high-gain mode

NIRSPEC/F070LP/G140H/H NIRSPEC/F170LP/G235H/H 14 NIRISS/ORDER 1/80P NIRISS/ORDER 1/256P KNOWN TRANSITS NIRISS/ORDER 2/256P TESS (M DWARFS ONLY) NIRSPEC/CLEAR/PRISM

16 4.0 3.9 3.8 3.7 3.6 3.5

Log Teff

ExoPAG 9 4 Jan 2014 13 Saturation limit vs wavelength

630 - 1050 420 - 1310 500 - 2000

6 420 - 1310 1900 - 3600

1900 - 3600 700 - 1300 1300 - 2300 1900 - 3600

700 - 1300 NIRSPEC/CLEAR/PRISM 8 NIRSPEC/F070LP/G140/M 500 - 850 700 - 1300 NIRSPEC/F100LP/G140/M NIRSPEC/F170LP/G235/M NIRSPEC/F290LP/G395/M NIRISS/ORDER 1/80P NIRISS/ORDER 1/256P J-band saturation magnitude NIRISS/ORDER 2/256P NIRCAM/F277W NIRCAM/F322W2 NIRCAM/F356W 10 NIRCAM/F410M NIRCAM/F444W

30 - 300

12 1 2 3 4 5 Wavelength (microns)

ExoPAG 9 4 Jan 2014 14 NIRISS First Light with the GR700 grism (GSFC, October 2013)

ExoPAG 9 4 Jan 2014 15 MIRI & FGS into ISIM

ExoPAG 9 4 Jan 2014 Real data vs simulation

CV1RR (October 2013)

Simulation

Excellent correlation between data and simulations.

ExoPAG 9 4 Jan 2014 17 GR700XD Monochromatic PSFs

0.64 um 0.64 um 0.64 um Monochromatic PSF Tilt at 0.64 µm Order 1 order 1 order 2 order 3 1619

1618

1617 Y position (pixel)

1616 Tilt = -1.0°

1615 330 340 350 360 370 380 X position (pixel)

1.06 um 1.06 um order 1 order 2

NIRISS grism is designed to have a PSF slanted by ~2° to mitigate undersampling problems.

ExoPAG 9 4 Jan 2014 18 NIRISS Transit Spectroscopy Simulations (photon-noise limited)

ExoPAG 9 4 Jan 2014 19 GJ1214b

Charbonneau et al 2009, Nature, 462, 17

What’s the nature of GJ1214b? GJ1214b Earth Neptune o An ice giant (a mini Neptune) ? o A water world ? Mass 6.5 1.0 17 Radius 2.7 1.0 4.0

Temperature 400-600 300 55 (Kelvin) Density 1.9 5.5 1.7 (g/cm3)

ExoPAG 9 4 Jan 2014 20 Current observations of GJ1214b HST/WFC3 At R=50 σ=230 ppm in 10 hr

Berta et al. 2012

Ground & space combined Limited by aperture, platform stability, detector and instrument systematics and atmosphere

ExoPAG 9 4 Jan 2014 21 The same observations with JWST/NIRISS

Water rich atmosphere ("Water world") GJ 1214b H2O rich atmosphere 0.9868 R = 165 0.9866 6.8 hr total 0.9864 σ = 70 ppm Flux(in)/Flux(out) 0.9862 170 ppm

JWST/NIRISS GJ1214b (M4.5V) J=9.8 τ=6.8 h (5 visits) R=165 at 1.25 µm

1.0 1.5 2.0 2.5 Wavelength (µm) f R H() 10 p f ⇡ R2 ✓ ◆atmo ? Same H = kT/µg model µ 18 ⇠

Credit: D. Lafrenière Model from Miller-Ricci et al. 2010

ExoPAG 9 4 Jan 2014 22 A more challenging observation…

An Earth analog around an M dwarf (R~100)

Feature Strength (ppm)

H20 5-15 Broad ozone CH4 ~10 feature CO2 5-30

O2 <5 JWST/NIRISS, ROSS238 (M5.5V), 3.2 pc O3 ~30 J=6.9 138 hrs (50 transits)

Model from Kaltenegger et al. 2009

ExoPAG 9 4 Jan 2014 23 A more challenging observation…

An Earth analog around an M dwarf (R~100)

Feature Strength (ppm)

H20 5-15 Broad ozone CH4 ~10 feature CO2 5-30

O2 <5 JWST/NIRISS, ROSS238 (M5.5V), 3.2 pc O3 ~30 J=6.9 138 hrs (50 transits)

Model from Kaltenegger et al. 2009

ExoPAG 9 4 Jan 2014 24 Performance limitations

5 ppm is about the noise level needed for minimal characterization of super-Earths. What will prevent reaching the photon-noise limit at this level?  Instrumental « red noise »  Already well-known from SPITZER and HST experience  Detector-related issues  Undersampling + jitter (may be okay with NIRISS)  Persistence  Long term stability (thermal instability)  Could probably be mitigated if noise is well characterized  Detailed simulations needed along with flight-like simulator testbed investigations.  Astrophysical « red noise »  Intrinsic variability (e.g. spots on M dwarfs)

ExoPAG 9 4 Jan 2014 25 The NIRISS Optical Simulator concept

ExoPAG 9 4 Jan 2014 26 Astrophysical noise associated with star spots

ExoPAG 9 4 Jan 2014 27 GJ1214b: are we seeing star spots?

• If GJ1214 is spotted over 5% of its surface and GJ1214b happens to transit a spot-free area … • Out-of-transit spectrum : 95% star, 5% spots • In-transit spectrum: 93.6% star, 5% spots • Spot spectra, 500 K cooler than photosphere, has signiﬁcantly deeper water bands and a redder overall SED. • In-transit/out-of-transit spectrum will contain signiﬁcant spectral structures at a level comparable to that induced by an exoplanet’s atmosphere

2 Rp/Rs=0.116, (χ r= 1.25) 0.124 2 Starspots, η=5%, Teff=3000K, ∆T=500K, (χ r= 1.03) 2 Solar, (χ r= 10.72) 2 No CH4, (χ r= 7.12) 2 H2O, (χ r= 1.30) 0.122 Berta et al. 2012 Bean et al. 2011

0.120 Star spot-induced transit s

/R spectrum ﬁts data better than p R 0.118 any planet atmosphere model!

0.116

0.114

Artigau et al, in prep.

1.0 1.5 2.0 2.5 Wavelength (µm)

ExoPAG 9 4 Jan 2014 28 Spectrum blueward of 1 µm may be key for discriminating between star spots and water vapor from the exoplanet.

1.005 TiO 1.005 TiO p p H2O

1.000 1.000 NaI Normalized R Normalized R H2O

0.995 0.995

Starspots Starspots Water−world Water−world Correlation : −7% Correlation : 84%

0.6 0.7 0.8 0.9 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 Wavelength (µm) Wavelength (µm)

• TiO, NaI, FeH dominate the star spot- induced spectrum. • In near-IR domain, both star spots and exoplanets induce very similar signals, Water absorption dominates the • both dominated by deep water features. planetary features. Slight difference in the shape spectra arise • Good spectral resolution needed to from the important difference in detect some features (e.g. NaI, KI) temperature (2500 K versus 500 K).

ExoPAG 9 4 Jan 2014 29 Summary

• NIRISS will be a powerful capability for high-precision transit spectroscopy work • Pros • Broad simultaneous wavelength coverage (0.7-2.5 µm) • Medium resolving power (~700). Unique capability < 1 µm. • Bright saturation limit (J<5) • Most of HZ transiting super-Earths from TESS should be observable. • Grism designed to mitigate undersampling problems. • Cons • Lower throughput compared to NIRSpec. May favor NIRSpec for deep observations provided NIRSPec’s noise floor is lower than NIRISS. • Detailed simulations and flight-like detector testbed activities needed to investigate and characterize systematic noise.

• Astrophysical noise (spots in particular) may be an issue for H2O detection on super-Earths. Broad wavelength coverage will key for discriminating between

genuine atmospheric H2O from residual stellar spot. • Let’s not give up too quickly on achieving photon-limited performance with JWST, especially with NIRISS !

ExoPAG 9 4 Jan 2014 30