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An integral field spectrograph for supernovae in space A.Ealet Marseille CCPM/CNRS

An integral field spectrograph for supernovae in space A.Ealet Marseille CCPM/CNRS. DE history. History. 1998 Discovery of the acceleration of the universe and dark energy using supernovae (SCP and High Z teams).

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An integral field spectrograph for supernovae in space A.Ealet Marseille CCPM/CNRS

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  1. An integral field spectrograph for supernovae in space A.Ealet Marseille CCPM/CNRS

  2. DE history History 1998 Discovery of the acceleration of the universe and dark energy using supernovae (SCP and High Z teams) . 2000 Confirmation of dark energy using cosmic microwave background measured from balloons. • 2003 Confirmation of dark energy using cosmic microwave background measured from space (WMAP). • First evidence of Baryon acoustic oscillation • And WE DO NOT KNOW AT ALL WHAT IS DARK ENERGY………… Anne EALET

  3. SN for Cosmology & DE • SNIa the most powerful and best proven technique. the outcome depending on the ultimate systematic uncertainties. • SNIa is an unique probe of DE because: • Independent of the growth of structure [in contrast to WL and BAO]. This is important when differentiating between DE and modified gravity models. • Probes luminosity distances [WL and BAO probe angular diameter distance and to some extent H]. • Allows for dense redshift- and spatial sampling which is important when constraining spatial and temporal variations of DE. Anne EALET

  4. Building the Hubble diagram 1.0 Fainter Constant acceleration 0.5 Concordance m, relative magnitudes 0.0 Freely expanding Hubble observations -0.5 Constant deceleration VISIBLE IR Brighter -1.0 0.0 0.5 1.0 1.5 2.0 Redshift, z Anne EALET

  5. Where we are today? • Today after 10 years… • about 1000 SNe Ia for cosmology • constant ω (state equation) determined to 5% • No strong information of time variation of w • accuracy dominated by systematic effects = calibration, reddening, evolution SNe + BAO + CMB... Anne EALET

  6. Methodologies Classical method used in most high z SN surveys (SNLS, Essence et..) Broad bands in photometry with a rolling search Spectroscopy mainly for redshift (host galaxy) and SNIa typing Caveat = inter calibrations (different filters at different redshifts) modeling with non flux calibrated spectra photometric corrections New paradigm Replace photometry by spectro photometry tested in nearby SN (Snfactory) (cf Bailey 09) and cfa (Blondin 10) -flux calibrated spectra at different epochs Benefit = synthetize any filters/redshift range sample of spectra for template modeling and understanding SN Simplify inter calibration with high z Difficulties = survey implementation and high z spectrscopy on ground Anne EALET

  7. Nearby SN on Snfactory Snfactory = a dedicted IFS In Hawai SN every 2-3 nights Use a photometric arm to correct Non photometric nights Build spectro photometric light curve Work on going , 58 published SNIa, calibration 2-3%

  8. More with spectroscopy Preliminary results Snfactory • - light curves at 2-3 % build with spectrophotometry • explore standardisation with spectroscopy alone • flux ratio as indicators as R642/543(Bailey 09) Single flux ratio produces better Hubble diagram than stretch + color corrections • - Other indicators can decorrelate color/redenning (under studies) This method is very promising to improve SN measurement for cosmology Spectro photometry and flux ratios require accurate relative flux calibration, as well as minimal contamination by host-galaxy light. Both requirements impose strong conditions on future SN Ia surveys for implementation Anne EALET

  9. Which spectroscopy for a future mission Going to high redshift classical method = SN followed in photometry + typing and systematic control (evolution) - Identify SNIa by the SiII line (large coverage for a large redshift range) + line ratios or any new possible indicators at peak =>good SNR => relative flux calibration and galaxy subtraction New paradigm = replace photometry by spectro-photometry -requires multi epochs follow up -relative flux calibration at 1-2% - galaxy subtraction Need more observational time but no photometry RCa RSi SiII Anne EALET

  10. Science requirements to specifications Si line Wavelength (µm) • Identification SN1a up to redshift 1.5 with Si line • Measure precisely some features =>relative spectro photometry ~ 2% • Subtraction of the host galaxy • Redshift of the host galaxy < 0.005(1+z) Ca Flux (photons) UV Anne EALET

  11. Why in Space? • Access to z > 1 with low systematic (NIR) • spectroscopic method for high z (z>0.3) is not possible from ground even in the visible (sensitivity) • Continuous, year-round observation of selected fields …essential for moving to 1-2% measurement ….essential for good spectroscopy Anne EALET

  12. Which Spectroscopy in space for SN • Slitless (as inJDEM /Adept/destiny) • Feasibility proven using HST/ACS • Multiplex advantage, time series • Need a wide field, deep survey • spectro-photometry? • Limited by the zodiacal background • IFU/slicer as in JDEM/SNAP (dedicated) Sensitivity = IFU or slit are more than 10 time more sensitive than slitless Need pointing (small FOV) Anne EALET

  13. Why an IFU/Slicer ? Very high sensitivity as a slit + detector noise optimisation SLICER = No need for accurate pointing Correct slit effect thanks to the slices All flux in the spectrograph No need of dithering Measures SN+galaxy in one shot => no ref image => easy to operate Pixel level simulation New HgCdTe detector can reduce exposure time using very low detector noise + long exposure time with up the ramp + cosmic rejection sky readout Z=1.5 exposure for SNR=18, D=1.5m Read noise (e) Anne EALET

  14. An IFU slicer spectrometer • IFU slicer in glass (French expertise) • Compact (20x30x10 cm) • Light < 12 kg • Galaxy and SN spectrum at the same time • Readiness TRL5 (CNES) • Full prototyping for performances IR path References • Aumeunier PASP,2008 • Ealet SPIE 2006,2008 • Prieto SPIE 2008 • Pamplona SPIE 2008 • Rossin SPIE 2006 Anne EALET

  15. R&D development (2005-2007) • A full demonstrator working in the visible and IR at 110 K • Validate the performances slicer concept and test the calibration procedure • Straylight Measurement controlled at 10-3 • Wavelength Calibration at the nanometer level • relative flux Calibration better than 1 % a NIR 2kx2k Rockwell device from Berkeley has been integrated and read with our own readout system Anne EALET

  16. Conclusion of Ifs/slicer prototype SNR Flux Error (%) Wavelength (nm) • Wavelength calibration • No need of object position • No need of dithering • Improve naturally the resolution • Good spectro photometry • All flux are in the slices • Correct slit effect thanks to slices in IR Real data demonstrator by Marseille team => redshift estimation < 0.003 (1+z) even with low resolution and sub sampled => accurate spectro-photometry even with no accurate pointing and low resution in visible Anne EALET

  17. Numerical model Sampled PSF Pixeled PSF Instrument design Point like source (x,y,λ) • Optical simulation (POP): • geometrical distorsions • aberrations • diffraction Detector pixelisation • Simulation of detector effects: • read noise • Dark current • inter and intra pixelvariation “real’’ PSF

  18. spectral slice 5 spectral slice 4 slice 3 slice 2 spatial slice 1 spatial MODELE NUMERIQUE Entrance FOV PSFs at the output of the optical simulation Core PSF (86 % du flux) Rings PSF (4 % du flux) On the detector Final PSF A monochromatic line A spectrum

  19. JWST/NIRSPEC IFU slicer • -NIRSPEC has a low resolution option (R=100) with slicer (Aluminium slices) • almost same concept than SNAP but optimised in [1-5] mm SNAP JWST Anne EALET

  20. JWST for high z SN spectroscopy • JWST/NIRSPEC can follow z >1 supernovae at peak in a reasonable amount of time • The coverage is not optimized for 0.2<z<0.8 (visible), and dominated by overhead • For at least 100-300 SN, this need a significant mission time (2 to 4 months) on target of opportunity + a coordination with an imaging wide survey to find them • A multi epochs approach with spectroscopy only is more difficult to implement on this non dedicated instrument NIRSPEC could do a good complement of follow up for very high z SN as target of opportunity But could not easily do a full spectroscopic program for cosmology Anne EALET

  21. JDEM ISWG studies A new optimised design http://jdem.gsfc.nasa.gov/science/iswg/JDEM_ISWG_Report.pdf SN strategy based on IFU/SLIT spectroscopy only To be implemented in WFIRST? Anne EALET

  22. Conclusion • Spectroscopy for high z supernovae for cosmology is a challenge for a future space mission • A new approach based on spectroscopy only is under consideration • Need a specific space instrument to have a high quality data sample • JWST / NIRSPEC can follow high z SN (z> 1 ) and can be a good complementary approach using target opportunity for a limited sample Need a coordination with a wide field survey • A dedicated program with a multi epochs should be better implemented in a future NIR wide field survey as the one planed for WFIRST. Anne EALET

  23. Anne EALET

  24. ASTRO2010 Released Aug. 13, the Astro2010 decadal survey — formally titled “New Worlds, New Horizons in Astronomy and Astrophysics” — designated WFIRST as the top priority for large missions for the decade ahead. The survey envisions WFIRST being developed by NASA in partnership with the U.S. Department of Energy and ESA at an estimated cost of $1.6 billion to study dark energy, hunt for Earth-like planets and advance scientific understanding of the nature and evolution of galaxies. Wfirst is an infrared telescope Lauch 2020-2022 Baseline Concept baseline = JDEM -1.5m telescope -36 IR detectors Scientific cases -dark energy with 3 probes (BAO,WL,SN) - exoplanets with micro gravitational lensing - guest investigator Anne EALET

  25. WHICH SENSITIVITY ? redshift redshift Sensitivity ~ 10-20 ergs/cm2/s/A = > ~1e-18 ergs/cm^2/s per spectral element (R=100) + SNR/spectral element > 10 at the above flux = > very challenging , time driver RCa RSi SiII Anne EALET

  26. Some results SNR Flux Error (%) Wavelength (nm) GOOD PSF at Room Temperature and at Operating Temperature (110K) ( compared with pixel level simulation) Good photometric measurement precision New method Insensitivity to slit effect Spectral resolution preserved even with PSF < slit No need of dithering Anne EALET

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