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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). - PowerPoint PPT Presentation
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An integral field spectrograph for
supernovae in space
A.Ealet
Marseille
CCPM/CNRS
HistoryHistory
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).
2005 First evidence of Baryon acoustic oscillation
And WE DO NOT KNOW AT ALL WHAT IS DARK ENERGY…………
IFU workshop 28 oct. 2010 2Anne EALET
DE history DE history
SN for Cosmology & DESN 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.
IFU workshop 28 oct. 2010 3Anne EALET
IFU workshop 28 oct. 2010
Anne EALET 4
Building the Hubble diagramF
ain
ter
Brig
hter
1.0
0.5
0.0
-0.5
-1.0
m, r
ela
tiv
e m
agn
itu
des
0.0 0.5 1.0 1.5 2.0
Redshift, z
Freely expanding
Constant deceleration
Concordance
Constant acceleration
Hubble observations
VISIBLE IR
• 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
Where we are today? Where we are today?
IFU workshop 28 oct. 2010 5Anne EALET
SNe + BAO + CMB...
w 0.969 0.061(stat) 0.065(sys)
MethodologiesMethodologies
6IFU workshop 28 oct. 2010 Anne EALET
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 spectraphotometric corrections
New paradigmReplace photometry by spectro photometrytested in nearby SN (Snfactory) (cf Bailey 09) and cfa (Blondin 10)
-flux calibrated spectra at different epochs
Benefit = synthetize any filters/redshift rangesample of spectra for template modeling and understanding SNSimplify inter calibration with high z
Difficulties = survey implementation and high z spectrscopy on ground
Nearby SN on SnfactoryNearby SN on Snfactory
7
Work on going , 58 published SNIa, calibration 2-3%
Snfactory = a dedicted IFSIn Hawai SN every 2-3 nights
Use a photometric arm to correctNon photometric nightsBuild spectro photometric light curve
More with spectroscopyMore with spectroscopy
8IFU workshop 28 oct. 2010 Anne EALET
- 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)
Preliminary results Snfactory
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
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
Which spectroscopy for a future missionWhich spectroscopy for a future mission
9IFU workshop 28 oct. 2010 Anne EALET
RCa
RSiSiII
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
10
Science requirements to specifications Science requirements to specifications Flu
x (
ph
oto
ns)
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)
Anne EALETmarseille Feb 05 09
bandwidth 0.4 to 1.7-2 µm cover Ca to SiII 0.3 < z < 1.7
FOV > 3’’ Galaxy +SN in one shot
spect resolution()/ pixel ~100 constant to not depend of the redshift
Spatial resolution 0.15’’ Reduce zodiacal light
Line precision 1 nm Redshift precision
spectrophotometry <2 % calibration
Throughput (optic+detector) > 40 % sensitivité
Sensitivity 10-20 erg/s/cm2/A Reach z>1.5 magnitude
UV
Ca
Why in Space?Why in Space?
IFU workshop 28 oct. 2010
Anne EALET 11
• 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
Which Spectroscopy in space for SN 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)
IFU workshop 28 oct. 2010
Anne EALET 12
Why an IFU/Slicer ? Why an IFU/Slicer ?
Pixel level simulation
13 Anne EALET
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
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
readoutsky
Read noise (e)
Z=1.5 exposure for SNR=18, D=1.5m
New HgCdTe detector can reduce exposure time using very low detector noise + long exposure time with up the ramp + cosmic rejection
14IFU workshop 28 oct. 2010 Anne EALET
An IFU slicer spectrometerAn IFU slicer spectrometer
IR path
Wavelength coverage (m)
0.4-1.70
Field of view 3.0" 6.0"
Spectral resolution, 70-100
Spatial resolution element (arc sec)
0.15
detectors HgCdTe18 m
Efficiency with OTA and QE
55% in NIR
• 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
References•Aumeunier PASP,2008•Ealet SPIE 2006,2008•Prieto SPIE 2008•Pamplona SPIE 2008•Rossin SPIE 2006
R&D development (2005-2007)R&D development (2005-2007)
15 Anne EALET
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 beenintegrated and read with our own readout system
IFU workshop 28 oct. 2010
Conclusion of Ifs/slicer prototypeConclusion of Ifs/slicer prototype
•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
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
IFU workshop 28 oct. 2010 16Anne EALETWavelength (nm)
Flu
x E
rror
(%)
SN
R
in IR
in visible
17
Numerical modelNumerical model
Instrument design
Optical simulation (POP): geometrical distorsions aberrations diffraction
Detector pixelisation
“real’’ PSF
Point like source (x,y,λ)
Sampled PSF
Simulation of detector effects: read noiseDark current inter and intra pixelvariation
Pixeled PSF
PSFs at the output of the optical simulation
Final PSF
Core PSF (86 % du flux)
Rings PSF (4 % du flux)
MODELE NUMERIQUE
slice 1slice 2slice 3slice 4slice 5
spatial
spectral
spatial
spectral
On the detector
Entrance FOV
A spectrum
A monochromatic line
JWST/NIRSPEC IFU slicerJWST/NIRSPEC IFU slicer
19IFU workshop 28 oct. 2010 Anne EALET
-NIRSPEC has a low resolution option (R=100) with slicer (Aluminium slices)
-almost same concept than SNAP but optimised in [1-5]m
SNAP
JWST
JWST SNAP/JDEM
Coverage [0.6-5] m [0.4-1.7]m
resolution 100 100
FOV 3’’x3’’ 3’’x6’’
sampling 0.1’’ 0.15 ’’
throughput 20 % 55 %
Detector noise 6 6
JWST for high z SN spectroscopyJWST for high z SN spectroscopy
IFU workshop 28 oct. 2010 20Anne EALET
• 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 fullspectroscopic programfor cosmology
NIRSPEC could do a good complement of follow up for very high z SN as target of opportunity
But could not easily do a fullspectroscopic programfor cosmology
21IFU workshop 28 oct. 2010 Anne EALET
JDEM ISWG studies A new optimised design
SN strategy based on IFU/SLIT spectroscopy only
http://jdem.gsfc.nasa.gov/science/iswg/JDEM_ISWG_Report.pdf
To be implemented in WFIRST?
Conclusion 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.
22IFU workshop 28 oct. 2010 Anne EALET
23IFU workshop 28 oct. 2010 Anne EALET
24IFU workshop 28 oct. 2010 Anne EALET
Wfirst is an infrared telescopeLauch 2020-2022
BaselineConcept 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
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.
ASTRO2010
25marseille Feb 05 09 Anne EALET
WHICH SENSITIVITY ?
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
redshiftredshift
RCa
RSiSiII
Some resultsSome results
26Anne EALET
GOOD PSF
at Room Temperature and
at Operating Temperature (110K) ( compared with pixel level simulation)
Insensitivity to slit effect Spectral resolution preserved
even with PSF < slit
No need of dithering
marseille Feb 05 09
Wavelength (nm)
Flu
x E
rror
(%)
SN
R
Good photometric measurement
precision
New method