comments on supernovae riess 2004 sample of snia comments on snia systematics next snia surveys some...
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Comments on Supernovae
• Riess 2004 sample of SNIa• Comments on SNIa systematics• Next SNIa surveys• Some Kosmoshow analysis of present SNIa data
Charling TAOApril 2004, Toulouse
SN Ia 2004 : Riess et al, astro-ph 0402512
Fits well the concordance model : 2= 178 /157 SNe Ia
183 SNIa selected Gold set of 157 SN Ia
SNIA 2004: Riess et al, astro-ph 0402512
* Low z : 0.01 < z < 0.15• Calan-Tololo (Hamuy et al., 1996) : 29 • CfA I (Riess et al. 1999): 22• CfA II (Jha et al, 2004b): 44 (not published yet)
16 new SNIA with HST (GOOD ACS Treasury program)
6 / 7 existing with z >1.25 + Compilation (Tonry et al. 2003): 172 with changes…
* Knop et al, 2003, SCP : 11 new 0.4 < z < 0.85
reanalysis of 1999 Perlmutter et al.
* 15 / original 42 excluded: inaccurate colour measurements and uncertain classification
* 6 /42 and 5/11: fail « strict SNIA » sample cut
* Barris et al, 2003, HZT: 22 new varying degrees of completeness on photometry and spectroscopy records
* Blakesly et al, 2003 : 2 with ACS on HST
Determination of Cosmological parameters
Riess et al, astro-ph 0402512
w=p/
w= w0+w’ z
Determination of acceleration
Riess et al, astro-ph 0402512
New physics?
• Cosmological constant• Dark Energy: Dynamical scalar fields,
quintessence…. General equation of state p=w r r = R-3(1+w)
Perhaps a bit early !!!
« Experimentalist » point of view…
Constraints on cosmological parameters
m= 0.2 - 0.3 effect!
Systematic error on magnitude
3 fit with no prior
20% calibration error on intermediate fluxes gives no cosmological
constant
Use Kosmoshow:
an IDL program by A. Tilquin!
marwww.in2p3.fr/~renoir/kosmoshow.html
Riess gold set sensitivity
Kosmoshow, A. Tilquin
A m=0.27 shift of low z data
No need for But Universe is not flat!
Shift z <0.15 data by m= 0.27
m= 0.43 +/-0.2 and = 0 +/-0.34
Use Kosmoshow: an IDL program by A. Tilquin!
Systematic differences between methods
A 3 steps method: o Discovery: subtraction of an image
with a reference one.
o Supernova type identification and redshift measurement: spectrum.
o Photometric follow-up: light curve.
Final analysis: Hubble diagram.
The “classical” observation method
m(z) = M + 5 log (DL(z,M,L))-5log(H0)+25
The Hubble diagram
Absolute magnitude
Less luminous/z =>Accelerated expansion less matter or more dark energy
Too luminous/z =>Slowed down expansion => decelerationMore matter, less dark energy
– Light Curve in local reference frame – K correction– Galactic extinction correction
- Standardisation methods : stretch (SCP), MLC2k2 (HiZ), m15, ...
mag
Magnitude at maximum
light curve
Standardisation: stretch method
Before: mB After : mBcor = mB – (s-1)
Precision on the magnitude dominated by intrinsic dispersion:
mint 0.15
Stretch uncorrected
Stretch corrected
Precision on the magnitude at the maximum
Fit cosmological parameters
– From Hubble diagram, fit best cosmological model agreeing with observations.
– Determine dark energy parameters , ou (X, w, w’)
and matter density M
Spectroscopy needed
• SN Ia Identification– Spectrum structure
• Redshift z measurement– From position of identified
lines from spectra SN and/or underlying galaxy
data analysis physics
The « classical » method
Images
Spectra
+ identification.
Ia
magnitude z(redshift)
galaxy
Hubble
Systematic effects
Extragalacticenvironment
Supernovaenvironment
reduction/correlationsSNIa contamination
Selection bias Inter calibration filters
local
Normal Dust absorptionLensingGrey DustSN evolution
Systematic effects
• Observational problems– Standardisation method– Light curve fitting
– Subtractions– Calibrations– Atmospheric corrections– K-corrections– Selection bias
– Heterogeneity of SN data– SNIa identification
• SN evolution
• Internal extinction not negligible in spiral galaxies
• Corrections for peculiar velocity effects
• Grey dust• Lensing
Rowan-Robinson astro-ph/021034
Perlmutter & Schmidt 0303428
Knop et al (2003) light curves
Spectrum is dilated by (1+z) :The integrated flux in a filter is Shifted. Filters responses are not flatSometimes, need different filtersCorrect for differences systematic effects
Le flux est intégré sur unfiltre pour un point dephotométrie
Redshift calibration
SNIa sample contamination
Need strict selection criteria Gold sample is probably well selected
Supernovæ identification
With SpectraMain stamp of the SNe Ia: Si II at 6150 Å:
o Hardly observable beyond z > 0.4-0.5.
Otherwise, search for features in the range 3500-5500 Å (supernova rest frame):
o Ca H&K, SiII at 4100 Å, SII, …
Ca H&K SiII 4100
Simulation of a SN Ia spectrum at
z0,5
Spectroscopy : a Supernovae
Atmospheric transmission (ground)
Reduction of transmission in visible Absorption water & O2 reduce visibility in IR .
Reduced efficiencyNot homogeneous filtersRedshift dependent !!!
Seeing+ weather+ moon+ field not always visibleabsorption
mmsz
arcmms
arcmms
///1050. :light maximumat SNIa 7.1
sec////1050. : Zodiacal
sec////10602 :Continuum
22
222
222
Les Atmospheric emission
Spectroscopy : Subtract galaxy
Dependence on SN Environment
Blue have a lower metallicity Can be seen further
Supernovae evolution Peak magnitude can change
– Explosion changes with environment– Difference of chemical elements around SN– Depends on galaxy morphology, age, type,…
Sullivan et al (2002) SCP
SNIa host galaxy morphological classification
Not a large effect, but statistics are low
Extinction and Dust
• Extinction by dust from Our or SN galaxy
Rv=3.1 +/- 0.3 for OUR galaxy Very large correction
• Grey dust: not well known, intergalactic,?
Before extinction
After correction
Correction factor to the magnitude
A = R* E(B-V) Measurements in many filters Select minimal dust regions ?
A strong limit on grey dust?
• A 24.7 hr Chandra exposure of QSO 1508-5714 z=4.3 shows no dust scattering halo
• Upper limit on mass density of large grained (>1m) intergalactic dust: dust < 2 10-6
Peerels, Tells, Petric, Helfand (2003)
Dust and evolution ?
Evolution: shift due to progenitor
• mass?• metallicity?• Ni distribution?• Other effects?
Dust :Homogeneous gray intergalactic dust?Galactic dust responsible for extinction?
Sensitivity to dark energy decrease for z > 0.6
Is there a region of deceleration? Needs to go to z> 1
Gravitational Lensing
Some estimates of Systematics
Effect of de/amplification
Systematics
Understand environmentTo classify and correct
Need precise measurementswith statistics
Perlmutter
SN demographics studies
Summary
Ideally• Many SN for a negligible statistical error and study of systematic conditions. wide field
• Detect deceleration zone (z>1) measure in IR (or have large local UV sample for SNIa identification) • Control the correction precision for SNIA standardisation (environment and measurement corrections)
• Control non corrected systematic effects to the same level Very precise light curves and spectra to determine the explosion parameters, at all distances.
space
Ground limitation at z around 1 due to atmosphere
ground simulation
Hubble diagrams: Space vs ground
Advantage of space
•More galaxy surface density•Less impact from a more constant PSF• More information on shape
same observation in space and from
ground
Optimisation of mission
SNAP a dedicated satellite
Large statistics: 2000 Sne Ia/yr redshift to z<1.7, Minimal selection Ia identification
2m wide field telescope
Science
• Measure M and • Measure w and w (z)
Data Set Requirements
• Discoveries 3.8 mag before max• Spectroscopy with S/N=10 at 15 Å bins• Near-IR spectroscopy to 1.7 m
Statistical Requirements• Sufficient (~2000) numbers of SNe Ia• …distributed in redshift• …out to z < 1.7
Systematics Requirements
Identified and proposed systematics:• Measurements to eliminate / bound each one to +/–0.02 mag
Satellite / Instrumentation Requirements
• ~2-meter mirror Derived requirements:• 1-square degree imager • High Earth orbit• Spectrograph • ~50 Mb/sec bandwidth (0.35 m to 1.7 m)
•••
•••
Mission : % level
Need same precision on extracted magnitude Fit the magnitude on light curve after corrections of stretch, galactic extinction, K-corrections, everything that modifies luminosity Study models and parameter extraction Determine camera properties
reach 1 to 2 % on cosmological parameters
SNAP goals
data analysis physics
SNAP: Observation method
Images
Spectra
+ same spectra, allows identification.
SiII Ia
magnitude
M ,
z(redshift)
galaxy
Hubble
The same !! But optimised for systematics
Discovery maximum 2 days (RF) after explosion ( max + 3.8 magnitude),
Ligth curve: At least 10 points in photometry until plateau (+2.5 m)
Spectrum very precise at maximum (identification, systematics, calibration)
SNAP SNIa strategy
Hubble Deep Field
Weak Lensing Survey
Supernova Survey
Surveys:• Supernova Survey:
• 2X7,5 sq. deg.• 2X16 months • R<30.4 (9 bands)
• Weak Lensing Survey• 300 sq. deg.• 0.5-1 year• R<28.8 (9 bands)
Each field is est observed ~4 daysAll images are cumulated
Observe repeatedly same
sky area
SNAP survey
Wide field !!
SNAP: control evolution systematics
Light curves
Multi band PhotometryPeak measurement 2 %K correctionSelection biasVery precise measurement of beginning and end of light curve
Simulated SNAP Light Curvesz=0.8 z=1.0
Rest R-band
Rest B-band
Rest V-band
z=1.2 z=1.4 z=1.6
Rest B-band
Rest V-band
SNIa Spectra
Wide lines!SII 5350Å, w = 200Å
SII “W”, w = 75Å
SiII 6150Å, w= 200Å
Study of spectra and correlation of line variations with explosion parameters and luminosity
Need MODELS
Quantification of systematics
Metallicity effect
Velocity differences
DataModels
Modelisation of explosion (T, v, M)
Control of evolution
Present errors on :(flat universe case)
statistics 0.085systematics (determination SCP)
Malmquist bias 0.04K correction/Calibration 0.025
Extinction by ordinary dust 0.03Extinction (galactic) 0.04Non SNIa 0.05
Gravit. Lensing <0.06
not determinedgrey dust ?SNIa evolution ?
SNAP
2000 SN
Detection at explosion
Adjust filters in B+ intercalibration
spectra colours SDSS/SIRF Spectra Id
Average on many SN
spectra NIR + z>1spectra z>1
A method for each systematics
Résultats-diagramme de Hubble SNAP Expectations
SNAP expected results
Weak Lensing + CMB
How to constraint systematic effects and get precise measurements?
• Ideally in space: SNAP/JDEM
Problem: > 2014
• In the meantime: More statistics from as homogeneous samples as possible
CFHTLS and ESSENCE + Nearby
Low z activities
•Nearby SuperNova Factory
–300 SNIa (2004-…)
–http://snfactory.lbl.gov/
•Physics of SNIa explosions
•Supernovae at CfA (ongoing…)
–Expect ~ 100
–http://cfa-www.harvard.edu/cfa/oir/Research/supernova.html
Low z: Nearby Supernova Factory (2004-…)
• Goals– ~100/yr 0.03<z<0.08– 10 spectro-photometric
between –14D and +40D – Spectra: 320-1000 nm
• Tools– Discovery: Two cameras (one
wide field) 1.2 m ground based telescopes: NEAT
– Lightcurve follow-up with YALO – Photo-spectro follow-up with Field
Integral spectrometre (SNIFS) for ground based 2.2m
telescope (Hawaii)
• Collaboration– France: CRAL,IPNL, LPNHE– US: LBNL, U.Chicago
Intermediate z (2003-2014)
• ESSENCE at CTIO– ~50 SN Ia/year– http://www.ctio.noao.edu/wproject/sne/
• SNLS with MEGACAM of CFHT Legacy Survey– MEGACAM working since march 2003– http://snls.in2p3.fr/– Foreseen : 700 SNIa z < 1.
The CFHT Legacy Survey Supernovæ Program
SNLS : the instruments
• A wide field camera (1 square degree, MEGACAM 0.35 Giga pixels) on 3.6 m CFHT (Hawaii) telescope
The Deep Survey of the CFHTLSCharacteristics:
o 4 fields of 1°x1° (RA=2h, 8h, 14h and 22h).
o Each field observed every 2-3 dark/grey nights (6 months/year).
o Each field observed with different filters:
[u’ (15 min)], g’ (15 min), r’ (30 min), i’ (60 min) and z’ (30 min).
o ~200 dark/grey nights exclusively dedicated to the survey (5 years).
o Seeing < 0.9 arcsec.
Pre-survey started in: March 2003.
Scientific objectives of the Deep Survey:
o Confirm acceleration with statistical significant study of systematics
o Characterization of the equation of state of the Dark Energy .
o Evolution of galaxies and quasars.
o Detection of transient phenomenæ.
o…
SNLS: Detections
Simulation of a SNIa light curve at
z=0.49
Multiplexing: detection and follow-up on the same image.
Light curve:
o Usable between 0.3 < z < 0.9: about 700 SNe Ia in 5 years.
o Between [-10,+15] days in the SN rest frame.
o Multi-wavelength: [g’], r’, i’ et z’.
Spectroscopic trigger: estimate of the magnitude and the date of the maximum.
Photometric follow-up
The spectroscopic program
Supernova type identification and redshift measurement.
Require 8-10 meters class telescope.About 12 SNe/field/lunation to be identified
Telescope allocation: Large Program on the ESO FORS/VLT:
240 hours spread over 4 semesters
Service mode.
Gemini:
3 Canada, 2 UK and 1 US nights/year requested.
Service mode.
Keck:
Visitor mode.
4 nights/year requested
Beginning of the pre-survey:o March 2003.
As expected, data not optimal at the beginning (engineering time):
o New optics (Megaprime), new camera (Megacam), new softwares, …
Dedicated spectroscopy program started July 2003 ~ 50 well measured SNIa todate!
The CFHT LS pre-survey and survey
Reference
Image
Subtraction
Sn2003fh: SN Ia at z=0.25
R6D4-9
Candidate
Ia:
z = 0.94
Age = -1 days
Preliminary
The CFHT Legacy Survey Supernovæ
Program
Canada and France
Extra collaborators for the spectroscopy:
VLT: ESO, Portugal, Sweden, UK.
Keck: US.
Gemini: UK, US.
Simulation after a 5 years survey
=0.72 and M=0.28.
SNFactory (300 SNe)
CFHTLS (700 SNe)
A new generation of Hubble diagram
SNLS : expected results
contraint
contraint
SN only : ~0.1 and w~0.2
limited to z<0.95 (atmosphere)
Flat
Only statistical errors
68 %
Comparison with present measurements
SNLS present conclusions
The CFHT LS /SNLS , a high redshift supernovæ factory:
o Survey started officially in August 2003.
o Sample increased by ~10: 700 Sne between 0.3<z<0.9.
o Very good quality and homogeneity of the data.
o Systematic errors at high redshift better controlled.
o Measurement of the w parameter at w 0.1.
o…
First results soon! (Already > 50 well measured SNIa)
Present situation:183 SN from Riess 2004
Astro-ph0402512
Curve for Gold sample
Fit, for a full sample, no prior
•Simulation and analysis tool:
Kosmoshow developed in IDL by André Tilquin (CPPM)
Kosmoshow analysis
marwww.in2p3.fr/~renoir/Kosmoshow.html
Riess 2004, gold sample
m=0.445 0.105
X=0.972 0.190
k=-0.418 0.283
Large presentr ?
Blanchard et al., (+ others) large r (0.1-0.2) for CMB possible
Riess gold sample radiative component
Simulation and analysis tool:
Kosmoshow (A.Tilquin)
Add r in DL equation: (1+z)4
component
Strong correlation r with M
Positive r component not excluded!
BUT always NEED large
Full fit on gold sample
T=1±0.1
Flat Universe
m=0.27±0.04
How can present r0 be large?
• Expected r0 = (1 + f N) = 5.06 10-5 h2
70
N = number of relativistic species Trec~ 0.26 eV
f = numerical factor = 0.227 for neutrinos
Expected (low z) r0 ~< 10-4 !!!With (1+z)4 evolution r,z=1100 is 103 higher than m with (1+z)3
evolution
Bias from the time evolution of the equation of state
astro-ph/0403285 Virey et al.
•Quantitative analysis of the bias on the cosmological parameters from the fitting procedure, ie, assuming a constant w, when it is not!
•With present statistics, can be ignored
Not the case with larger samples!
Example of bias: large w1
• w0F=-0.7
• w1F= 0.8
Suggestion Maor et al...
4-fit
Ms, M, w0 , w1
3-fit,
Ms, M, w0
Comments on Supernovae: a summary
• Riess 2004 sample of SNIa: a strict selection• Comments on SNIa systematics. Not all understood!• Next SNIa surveys• Some Kosmoshow analysis of present SNIa data
Charling TAOApril 2004, Toulouse