Prospects – JWST, EUCLID, WFIRST

1. Prospects – JWST, EUCLID, WFIRST Jeff Kruk (GSFC) Jeffrey.Kruk@nasa.gov

2. Outline • HST: now to 2015 and beyond… • JWST: 2015 - 2025 • EUCLID(?): 2018-2023 • WFIRST: XX - XX+5… J. Kruk STScI Slitless Spectroscopy wkshp

3. Sky backgrounds J. Kruk STScI Slitless Spectroscopy wkshp

4. HST slitless modes J. Kruk STScI Slitless Spectroscopy wkshp

5. JWST slitless modes *NIRSpec micro-shutters: 0.2”x0.45” - open area ratio is 0.7 if all left open J. Kruk STScI Slitless Spectroscopy wkshp

6. EUCLIDNIR slitless spectroscopy • Launch in 2018 if selected, 5 year mission duration • Survey 20000 deg2 • limiting line flux 4*10-16 ergs/cm2/s • Characteristics (Laureijs et al 2010 SPIE 7731): • 1.2m primary, 0.35m secondary obscuration • 4 grisms in wheel, identical except for 90° rotations • 1.0-2.0 microns • R=500 • Focal plane: (choice still TBD?) • 12 SCAs: 0.33”/pix 36.4’x48.5’ (0.49 sq deg) • 16 SCAs: 0.31”/pix 46.1’x46.1’ (0.59 sq deg) J. Kruk STScI Slitless Spectroscopy wkshp

7. WFIRST • Launch: ?? - depends on JWST schedule • Mission duration: 5 years min, 10 years goal • Objectives: • 10000 deg2 WL survey (30 gal/sq arcmin) • 20000 deg2 BAO survey (limiting flux 1.6 10-16) • 150 SNIa per z=0.1 • (didn’t quite fit into 5 years, but close) • EOS panel recommendations cuts time in ~half for first 5 years of mission J. Kruk STScI Slitless Spectroscopy wkshp

8. WFIRST characteristics(details subject to change!) • Imager • 0.4-2.0m • 0.18”/pixel • 4x6 array of SCAs (0.25 deg2) • Filter wheel: 5 filters, R=75 prism, blank • Spectrometers (2, w/ opposing dispersions) • 1.1-2.0m • 0.37”/pixel • 2x3 array of SCAs (0.26 deg2) each • R=270-327 per 2 pixels • R = 200-240”, or c/R = 1500-1250km/s/arcsec J. Kruk STScI Slitless Spectroscopy wkshp

9. WFIRST block diagram(details almost certain to change) J. Kruk STScI Slitless Spectroscopy wkshp

10. WFIRST focal planes as projected onto the sky J. Kruk STScI Slitless Spectroscopy wkshp

11. Design Tradesgrism vs. prism Grism pros: • zero-order gives wavelength reference • Allows higher dispersion Grism cons: • Zero order increases spectral contamination • Higher dispersion not needed for BAO; if lines resolved, S/N is reduced • Higher orders contaminate spectra • 1st order throughput lower than prism Grism simulation courtesy of David Larson J. Kruk STScI Slitless Spectroscopy wkshp

12. Design Trades • Dispersion • σz/(1+z) < 0.001, resolve OIII, don’t resolve Hα • Bandpass • Redshift coverage & spectral diagnostics vs zodiacal light • Combined w/dispersion -> length of spectral trace • Number of roll angles, size of roll offset • 4 rolls: 0°,5°; 170°,175° found sufficient • Don’t set 2 spectrometers exactly 180° apart J. Kruk STScI Slitless Spectroscopy wkshp

13. Imager sim – 225 sec Imager simulation – 225sec 1SCA (log stretch) Courtesy David Larson J. Kruk STScI Slitless Spectroscopy wkshp

14. Spectrometer simulation – 225 sec 1SCA (log stretch) Courtesy David Larson J. Kruk STScI Slitless Spectroscopy wkshp

15. 4° roll offset Roll = 0 Roll = 4 J. Kruk STScI Slitless Spectroscopy wkshp

16. 133 ksec deep exp (SN field) asinh stretch Galaxies & stars only - no background Courtesy David Larson J. Kruk STScI Slitless Spectroscopy wkshp

17. General issues • EUCLID, WFIRST not as clean as HST • PSF, pixels are large compared to HST • Pointing stability, dithering, less precise than HST • What dithering is desirable/required in this context? • Direct images are obtained with a different instrument at different times • Use edges of traces of bright stars in field for registration J. Kruk STScI Slitless Spectroscopy wkshp

18. Issues continued:calibrations BAO needs accurate wavelengths • Optical distortion calibration is critical – not challenging SNIa needs accurate fluxes • If from spectra, flat-field cube is critical – challenging • Would like to derive flat-field internally from the data • Has been done for imaging instruments (Arendt et al. 2010 ApJS 186 10) • Dimensionality of problem is higher for slitless spectrometer; will need extensive simulations to test Persistence corrections • Can pipeline maintain continuous exposure history? • Initial planning limited to DE programs • Need to reevaluate for larger WFIRST program J. Kruk STScI Slitless Spectroscopy wkshp

19. Issues cont. • Datasets are large! • Manual processing not practical for 109 galaxies • Extract ~109 to obtain 108 emission-line galaxies • “…it is still mandatory to check and validate the products before any science investigation can commence.” (The WFC3 IR Grism Data Reduction Cookbook – Extracting several 100 grism spectra made easy) J. Kruk STScI Slitless Spectroscopy wkshp

20. Issues cont. • Datasets are large! • Manual processing not practical for 109 galaxies • Extract ~109 to obtain 108 emission-line galaxies • “…it is still mandatory to check and validate the products before any science investigation can commence.” (The WFC3 IR Grism Data Reduction Cookbook – Extracting several 100 grism spectra made easy) Uh Oh….. Crowd-sourcing? Doesn’t look like as much fun as the Galaxy zoo J. Kruk STScI Slitless Spectroscopy wkshp

21. WFIRST - what’s next? • Astro-2010 provided fairly strict guidance, • But details left open for further optimization • The science goals have expanded to fill a 10-year mission. • While plausible, the nominal design life is 5 years (so everyone starts out unhappy) • The Science Definition Team may have a big role in defining the details. Stay tuned. J. Kruk STScI Slitless Spectroscopy wkshp

22. WFIRST telescope trade:1.5m on-axis vs 1.3m off-axis Encircled Energy PSF - scaled by effective area Diffraction from spider arms not included J. Kruk STScI Slitless Spectroscopy wkshp

23. EOS observing plan • BAO+WL: <~2 years • Sne: 0.5 years • Micro-lensing (Galactic bulge): 1.4 years • Galactic plane survey: 0.5 year • Guest-observer surveys: 1 year • This means you! J. Kruk STScI Slitless Spectroscopy wkshp

24. WFIRST SDT Deadline for applications to the WFIRST Science Definition Team: Nov 23rd, 2010 Please Apply! Further info: http://wfirst.gsfc.nasa.gov J. Kruk STScI Slitless Spectroscopy wkshp