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