metrology of type ia supernovae for cosmology claire juramy – supernovae group –...
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Metrology of type Ia supernovae for cosmology
Claire JURAMY – Supernovae Group – LPNHE/IN2P3/CNRS
ACKS seminar December 7, 2006
Claire Juramy 2
• Cosmology measurements with type Ia supernovae• Combined « calorimetric » analysis
• Modeling of type Ia supernovae
• Simulation of radioactive products deposition
• Analysis of late time spectra
• « Green ray » estimator
• Instrumentation for a large focal plane camera• ASIC for CCD readout in large mosaic detectors
• Cryogenic test bench
• Calibration by direct illumination with LEDs
Claire Juramy 3
Expansion and content of the universe
• Homogenous, isotropic universe + general relativity
Friedman equations :
• R : scale factor, H : expansion rate, k : curvature
• Accelerated expansion : Cosmological constant : w = -1, w’(z) = 0
Dark energy : equation of state wX = pX / X < - 1/3
)3(3
4
3 2p
c
G
R
R
22
2
2
33
8
R
k
c
G
R
RH M
120
20
MHR
k
z
Xm dzz
zwzHzH
0
320
2 ''1
)'(13exp1)(
Claire Juramy 4
Cosmological distance measurements • Cosmological redshift :
• Cosmological distances :
– Angular diameter dA
– Proper motion dM
– Luminosity distance dL :
• Comoving density
ztR
tR
e
r
e
r 1)(
)(
24 L
emobs
d
PF
AML dzdzd 211
Claire Juramy 5
Observation of SNe Ia in SNLS• Detection
• Spectrum : identification, redshift
• « Multiplexed » follow-up (MegaCam)
Type Ia, z = 0.93, VLT
Claire Juramy 6
Measurements of dL with SNe Ia (1)
• Measurement of flux in several filters (u*g’r’i’z’)
« Flat fields » for detector calibration
Point Spread Function fitting
Calibration with standard stars, atmospheric extinction
Corrections due to differences in filters (UBVRI) and spectra
Claire Juramy 7
Measurements of dL with SNe Ia (2)
• Nearby and distant supernovae : flux in restframe filters, cross-filter calibration
SuperNova Factory : SNe Ia spectrophotometry at low z• Empirical relations to reduce the dispersion of instrinsic
luminosities (Pem) : « stretch » and « color »
SNLS : SALT (Spectral Adaptative Lightcurve Template) : fits measured lightcurves to get mB*, s, c
Distance modulus :
B = mB* - MB = 5 log(dL/10pc)
Absolute magnitude :
MB = M - (s-1) + c
Claire Juramy 8
Cosmological results with SNLS
M = 0.271 + 0.021 (stat) + 0.007 (sys)
w = -1.023 + 0.087 (stat) + 0.054 (sys)
Claire Juramy 9
• Cosmology measurements with type Ia supernovae• Combined « calorimetric » analysis
• Modeling of type Ia supernovae
• Simulation of radioactive products deposition
• Analysis of late time spectra
• « Green ray » estimator
• Instrumentation for a large focal plane camera• ASIC for CCD readout in large mosaic detectors
• Cryogenic test bench
• Calibration by direct illumination with LEDs
Claire Juramy 10
• White dwarf C+O, companion, Chandrasekhar mass (1.38 M)• Thermonuclear explosion : intermediate mass elements (Si,
Mg, Ca), 56Ni, iron peak elements Ejecta speed ~10,000 km/s• Decay of radioactive elements :
56Ni ( = 8.8 j) → 56Co ( = 111 j) → 56Fe Lightcurves
Type Ia supernovae
Claire Juramy 11
• Photospheric phase, nebular phase
• “Calorimetric” behavior : total energies, nebular phase
Supernova evolution
SN 1990N
Bmax + 255 j
Å
Claire Juramy 12
Model for gamma ray escape• Simulation of the decay of radioactive elements and of the
absorption of the products (, +) in the expanding supernova
• Physical parameters : 56Ni mass, kinetic energy (density profile, maximal speed), stratification
• Photoelectric effect, Compton scattering (E < 4 MeV)
Claire Juramy 13
GRATIS (Gamma Ray Absorption in Type Ia Supernovae)
• Monte-Carlo
• Propagation along a fixed axis : computing speed, decorrelates direction and energy after Compton scattering
Decay total
Absorbed total
Absorbed in Ni
Absorbed in Fe
Absorbed in Si
Monte Carlo
Direct
Claire Juramy 14
Results from GRATIS
• Deposited power depending on nickel mass mNi and ejecta speed vmax
• Simulation based only on physical parameters
mNi = 0.3 to 1.0 MVmax = 11,000 to 19,000 km/s
Claire Juramy 15
Comparing GRATIS to observations• Bolometric lightcurves : SALT, absolute calibration• Agreement (50 % efficiency), dispersions• Relations between parameters (mNi, vmax) and (s,c)• Limits of SALT for bolometry and at late times
Claire Juramy 16
Late-time spectra decomposition• Publicly available SNe Ia spectra : low signal, few spectra,
quality of data
• Normalized in flux on common interval• Very late-time vector (>+200 d) + orthonormal vector (60 to
200 d)
Claire Juramy 17
Co and Fe components• Projection, linear with %Fe in 56Co → 56Fe• Templates for “Co” and “Fe” • Not enough data for “calorimetry” : cannot determine relative
scintillation efficiency of Co and Fe
200 j60 j
Claire Juramy 18
Color during Co Fe phase
• “Lira” relation for unreddened SNe Ia
Claire Juramy 19
“Green ray”• Fast change in color, transition towards emission spectrum
• Optimal estimator : selected peaks, practical : two sharp filters below and above ~5350 Å
• Quantities : speed, phase and height of the color jump
Flux ratio between filters / same around Bmax
Claire Juramy 20
Measurement of the green ray
• SNLS filters : r’/g’ restframe, i’/r’ at z = 0.35
g’ r’ i’ z’
Claire Juramy 21
Green ray time and stretch parameter
• i’/r’ correlates with stretch within redshift range around 0.35
• Common physical origin
Better evaluation of the “stretch” parameter
Claire Juramy 22
• Cosmology measurements with type Ia supernovae• Combined « calorimetric » analysis
• Modeling of type Ia supernovae
• Simulation of radioactive products deposition
• Analysis of late time spectra
• « Green ray » estimator
• Instrumentation for a large focal plane camera• ASIC for CCD readout in large mosaic detectors
• Cryogenic test bench
• Calibration by direct illumination with LEDs
Claire Juramy 23
Large mosaic detectors projects• Possible improvements for cosmology
with supernovae : increase number, higher redshifts, decrease systematic errors
– Large focal plane
– Optical (CCDs) and/or IR detectors
– Dedicated campaigns
• Projects :
– In space : SNAP (~ 700 Mpixel, 0.7deg², CCDs and IR up to 1.7 m), others : JDEM, DUNE
– On the ground : LSST (> 3 Gpixel, 10 deg²), others
SNAP
MegaCam (CFHT)
Claire Juramy 24
Readout electronics for large mosaics• Constraints on front-end electronics : temperature, power,
irradiation (in space)
Integrated electronics : compact, low power, adapted to low temperatures, radiation hardness / extra noise, limited voltage
• « Video » chip : analogic functions, ADC
• First ASIC : testing of analogic functions - AMS 0.35µ
Claire Juramy 25
CCD readout
• Readout capacitor ~ 40 fF, 4 µV/e-
• Reset noise
• Correction strategies :
• Clamp and Sample : reset to reference voltage
• Dual Slope Integrator : measure of reference and signal, subtraction
eVCTkBV 80320/
Claire Juramy 26
DGCS (Dual Gain Clamp and Sample) ASIC • 17-bit dynamic : 2 e- (CCD noise) to 250,000 e- (CCD well
capacity) – 4 µV/ e-
• Voltage range : +1.5 / - 3.5 V or + 2.5 V
• Readout speed (~1MS/s) : ADC comparator limits dynamic to ~14 bits
• Dual gain solution (x 3 et x 96) + 2x 12-bit ADCs
• Clamp / DC restore
27
DGCS ASIC : functional testing• Offset and gain problem on high gain channel : x 60, - 600 mV
• Identification and measurement of parasitic resistors
• Linearity up to specifications
Low
gai
nH
igh
gain
LSB 12 bits
parasitic R
Claire Juramy 28
Acquisition for noise measurements
• Measurements to < 1 µV
• Input resistors : simulate detector noise
• Fast digitizing (1 GHz), off-line analysis
Claire Juramy 29
ASIC DGCS : low noise analysis
• Noise spectra• Thermal noise of
input resistors• Intrinsic noise at
optimal readout time (80 µs) : – x 60 : 1.1 µV– x 3 : 1.8 µV
• Simulation package validated
1 MΩ20 kΩ2 kΩ500 Ω50 Ω
parasitic Cparasitic R
Sim
ulat
ion
Mea
sure
s
Low gain High gain
Claire Juramy 30
1/f noise
• 1/f noise dominant at low frequencies (20 kHz) • Conforms to simulation
Measurements
R = 50 to 1 M
Simulation
R = 500 k and 2 k
Claire Juramy 31
Clamp and Sample vs. Dual Slope Integrator
• C&S : longer integration time for equal pixel time, single clock, clamp noise
• DSI : low frequency noise suppression, need DC restore function, need precision on timing
DSI 2 kΩ
DSI 500 Ω
DSI 500 Ω (no aliasing)
C&S 500 Ω
Readout noise Clamp noise
½ e-1 e-
Claire Juramy 32
Cold and irradiation tests
• Functioning down to 130 K
• Irradiation with cobalt 60 source (180 krad) Viable solution for mosaic readout in ground and space projects Future developments : adding ADCs, Low Current Amplifier
Claire Juramy 33
Cryogenic test bench
• Dual cooling system
• Flexibility
• Temperature and pressure monitoring
• Focal plane : detector, calibrated photodiodes, readout ASIC
• Isolation from EM noise
Claire Juramy 34
Cryogenic commissioning• Cold screen ~ 100 K• Cryogenerator : focal plane ~ 70 KAvailable for future electronic tests
95 K
145 K
ASIC
N2 entrance
cold screen
Claire Juramy 35
SNDICE : SuperNova Direct Illumination Calibration Experiment
• Photometric calibration for SNLS : instrumental calibration• LED properties• Direct illumination setup :
– Less stray light– Controlled flux– Alignment
• Wavelength range : ~20 LEDs• Precision, accuracy :
– Calibrated source – Feedback for stability
– Additional check
Claire Juramy 36
Proposed system architecture
(Cooled Large Area Photodiode)
Camera support beam
Focal plane
Out of the light path
LED sourceDACs
computer
LCAs Mux ADC
FPGAx 20
x 20
T
CLAP
(Low Current Amplifier)
MegaCam
Claire Juramy 37
Low Current Amplifier ASIC• Prototype
• Optimization of input transistor for ultra low input current : guard rings
Claire Juramy 38
Developments and tests
• Preliminary calibration work on test bench :– Calibration of LEDs : X, Y, T, spectrum, stability with
feedback
– Cross-calibration of CLAP with NIST standard
x 20 s
70 fA
Claire Juramy 39
First LED test results
• Oversampling of the beam (photodiode: 2.4 mm)• Subtraction of dark current, comparison of flux to
reference at regular intervals
Claire Juramy 40
First LED test results • Irregularities at the percent level• Need to design second diaphragm hole to avoid
glancing reflexions
Claire Juramy 41
Conclusion
Claire Juramy 42
Détecteurs : CCD du LBNL
• CCD épais haute résistivité du LBNL : « back-illuminated », sensibilité de l’UV au proche infra-rouge, pas de « fringing »
• Forte tension de biais, polarité inversée
Claire Juramy 43
Active Pixel Sensor infra-rouge
• Substrat photosensible HgCdTe ou InGaAs
• Matrice de lecture : « BareMux »
• H2RG (Rockwell) : pixels de référence, fenêtres
• Bruit « extra noise » : supprimé par nouveau procédé
Mesuré
Attendu
Objectif
Claire Juramy 44
Banc de test CCD• Refroidissement à l’azote liquide• Suivi de la température et de la pression• Plan focal : photodiodes calibrées• Lecture CCD : contrôleur SDSU,
intégration système LPNHE• Éléments optiques
Claire Juramy 45
Cryogénie du banc CCD• Suivi de la température et de la pression
• Performances du refroidissement : 150 K au niveau du CCD
Claire Juramy 46
Performances du banc infra-rouge• Écran froid
• Refroidissement du plan focal (plaque molybdène)
Claire Juramy 47
Acquisition CCD• Contrôleur SDSU
• Lecture : SDSU, ASIC, DSA
Claire Juramy 48
• Thermonuclear energy ~ 10 x decay energy• 56Ni : lowest energy/A for Z = A/2
Burnt elements
Claire Juramy 49
Comparing GRATIS to observations : total• Bolometric lightcurves : SALT, absolute calibration
• Agreement (50 % efficiency), dispersions
• Relations between parameters (mNi, vmax) and (s,c)
Claire Juramy 50
Comparing GRATIS to observations : power• Same efficiency (50 %)
• Heavy influence of vmax
• Limits of SALT for bolometry and at late times
Claire Juramy 51
Spectres des phases tardives
• Données rares
• Phases :
– Saut de couleur (rayon vert)
– 56Co 56Fe
– Fer dominant
Claire Juramy 52
• Masse de nickel 56
• Système progéniteur, explosion
• Géométrie : non sphérique, étoile compagnon
• Absorption, rougissement par des poussières
• Galaxie hôte
Diversité des supernovae de type Ia
Claire Juramy 53
Proposed system architecture
(Cooled Large Area Photodiode)
(LED source)
Camera support beam (« spider »)
Focal plane
Out of the light path
Claire Juramy 54
Electronic card
• Low Current Amplifier
LED source DACs computer
LCAs Mux ADC
FPGAx 20
x 20
T
CLAP