C. Tao, Chamrousse 2004 Comments and Questions about the Dark Universe Charling TAO CPPM &...
-
Upload
margaret-stevens -
Category
Documents
-
view
225 -
download
3
Transcript of C. Tao, Chamrousse 2004 Comments and Questions about the Dark Universe Charling TAO CPPM &...
C. Tao, Chamrousse 2004
Comments and Questions about the
Dark Universe
Charling TAO
CPPM & Université de la Méditerranée
Chamrousse, Dec. 2004
C. Tao, Chamrousse 2004
WMAP
Cosmic Microwave Background
A mysterious Universe
Definition: c (c=10-29 g/cm3)
Position 1st peak =1.02 +/- 0.02Flat universe
Ratio (2/1) peaksB =0.046 +/- 0.006
Ordinary Matter: 4%
2/3
Dark Energy
1/3 Dark Matter
CMB, + SN, clusters, galaxies redshift surveys, Weak Lensing, …
Concordant CDM model with
Cold Dark Matter and Cosmological constant
C. Tao, Chamrousse 2004
1) Brief introduction on SN
2) Present SNIa data
3) Determination of cosmological parameters: a concordant or a convergent Universe?
4) « Experimentalist » point of view: SNIa: « 2 » effect?
Perhaps too early to speak about new physics !?!
5) How can SN results be improved?
6) Need for more theoretical work
7) What about Cosmology tests in laboratories?
Outline of the presentation
C. Tao, Chamrousse 2004
Supernovae•Exploding stars Brightest objects in Universe
• Can sometimes be seen by eye rare! 8 recorded in 2000 years
• Historical (super) novae
Chinese records 185, 369, 1006 (arabo-persian also), 1054, 1181.
1054: Crab Nebula (M1) intense radio, X and gamma emission
-1572 (Tycho Brahe),1604 (Kepler)
visible during the day
-1987A LMC : UV, X, radio, visible, + neutrinos !
C. Tao, Chamrousse 2004
Historical SN Classification
• Type I : absence of hydrogen
+Type Ia: presence of ionised Silicium (SiII)
+Type Ib: absence of silicium, presence of helium
+Type Ic: absence of silicium and helium
• Type II: Presence of hydrogen H and H
+ Type II normal: domination of hydrogen, presence of helium. IIL (linear) or IIP (plateau) according to Light curves
+Type IIb : Dominating presence of helium
• Peculiar types
C. Tao, Chamrousse 2004
Supernovae: explosions
Core Collapse SN
SNIa : 2 stars (a white dwarf +…)
Red giant
White dwarf
Chandrasekhar mass 1.4 MO
C. Tao, Chamrousse 2004
Interest of SN study
• Cosmology: distance indicators (SNIa)
• Physics of galaxies: ISM heavy elements and star formation
• Physics of stars: explosion at end of star life
• Particle Physics: neutrinos properties
• Philosophy: We are all star dust
C. Tao, Chamrousse 2004
Measuring distances
D(t) = a(t) D(t0)
Cosmology: additional a(t) scale factor
a(t) = a0(1+ H0t -1/2 q0 (H0t)2 + …)
H0 = Hubble parameter measures the expansion rate of the Universe
H0= (.a/a)0 = 100 h km/s/Mpc , h= 0.72 +/- 0.05 (?)
q0 = deceleration parameter A Universe with only matter is expected to decelerate
SN 1996
C. Tao, Chamrousse 2004
Less luminous/z =>Accelerated expansion less matter or more dark energy
Too luminous/z =>Slowed down expansion => decelerationMore matter, less dark energy
m(z) = M + 5 log (DL(z,M,L))-5log(H0)+25
The Hubble diagram with SNIa
Absolute magnitude
C. Tao, Chamrousse 2004
A 3 steps method:
o Discovery: subtraction from a reference image.
o Supernova type identification and redshift measurement
o Photometric follow-up:
The “classical” SN observation method
Final analysis: Hubble diagram.
light curve
spectrum
C. Tao, Chamrousse 2004
SN are not exact standard candles!
The light of SNIa explosions can be followed up for several weeks with telescopes
C. Tao, Chamrousse 2004
Different standardisation methods
Before: mB After, eg, stretch correction: mBcor = mB – (s-1)
Different standardisation methods : stretch (SCP), MLC2k2 (HiZ), m15, ...
C. Tao, Chamrousse 2004
data analysis physics
The « classical » method
Images
Spectra
+ identification.
Ia
magnitude z(redshift)
galaxy
Hubble
C. Tao, Chamrousse 2004
Fit cosmological parameters
• From Hubble diagram, fit models
• Determine dark energy parameters , or (X, w, w’) and matter density M
z 1
mag
C. Tao, Chamrousse 2004
SNIa
SURPRISE: acceleration!!!
q0 negative
= (t)/c(t) =
k
/3H02
q0= 1/2< 0
•Search for light curves by photometry
•Identification of SNIa by spectrometry
z
C. Tao, Chamrousse 2004
2) SN Ia : the present status a selection by 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
16 new SN Ia with HST (GOOD ACS Treasury program)
6 / 7 existing with z >1.25
+ Compilation (Tonry et al. 2003): 172 with changes from…
* 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
C. Tao, Chamrousse 2004
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
M=0.29
=0.71
Prior: Flat UniverseBut also
non concordant models
C. Tao, Chamrousse 2004
Determination of Cosmological parameters
Riess et al, astro-ph 0402512
w=p/
w= w0+w’ z
C. Tao, Chamrousse 2004
Simulation and analysis tool: Kosmoshow
developed in IDL by André Tilquin (CPPM) marwww.in2p3.fr/~renoir/Kosmoshow.html
Recent phenomenological work on SNIa
Collaboration CPT/CPPM
Virey, Ealet, Tao, Tilquin, Bonissent, Fouchez, Taxil astro-ph/0407452
C. Tao, Chamrousse 2004
Example of possible bias: large w1
4-fit
Ms, M, w0 , w1
3-fit,
Ms, M, w0
Suggestion Maor et al...
• w0F=-0.7
• w1F= 0.8
•M = 0.3Bias 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!
Beware of fitting method !!!
With present statistics, can be ignored
Not the case with larger samples!
C. Tao, Chamrousse 2004
• SN data seem to prefer larger m
• Instability of results with fits• Errors on w1 are ”small” only if m ~ 0.3
(157 SN Ia « gold sample » Riess et al., astro-ph/040251)
w = p/= w0+ w1z
Riess et al. SNIa data: results for different fits
Results Riess et al…
C. Tao, Chamrousse 2004
•With prior M = 0.27 +/- 0.04, always CDM (ie w=-1) reconstructed, even with different assumptions in simulations , eg, M = 0.48 , w=/=-1
CDM convergent model !?!
3) Reanalysis of Riess et al. SNIa data
Virey et al., astro-ph 0407452A concordant or a converging Universe
?
• Without flat prior, NO strong constraints from SNIa
• Prior: Flat Universe , but no prior on M
SNIa M = 0.48 preferred value
sM = 0.27 +/- 0.04 ???
C. Tao, Chamrousse 2004
Many determinations of M
2dFGRS Hawkins et al., astro-ph/0212375 MNRAS, only bias Tegmark et al. astro-ph/0310725 3D power spectrum of galaxies from SDSS astro-ph/0310723 Cosmological parameters from SDSS and WMAP,Clusters, Weak Lensing, etc….
Riess et al., astro-ph/0402512 SNM = 0.27 +/- 0.04
N. Bahcall et al. Comparison M/L data/simulation M = 0.16 +/-
0.05
S. Vauclair et al. XMM X-ray clusters M > 0.85
WMAP: CMB
Bennett et al., 2003 ApJS, 148, 1 with h=0.71 +/- 0.05 0.27 +/- 0.04
Spergel et al. 2003 ApJS, 148, 175
CMB aloneM h2 = 0.14 +/- 0.02 0.27 +/- 0.10
CMB + 2dFGRS Mh2 = 0.134 +/- 0.006 with h=0.72 +/- 0.05 0.26 +/- 0.04
Freedman and Turner, Rev.Mod.Phys. (astro-ph/0308418) M = 0.29 +/- 0.04
X
C. Tao, Chamrousse 2004
WMAP cosmological parameters (Table I)
) CDM, ie, flat Universe and equation of state w =p/ = cte (= -1)
2) Measures m h2 and b h2 fb = b/m = 0.17 +/-0.02
C. Tao, Chamrousse 2004
M = 0.47, w=-0.5 and h=0.57 => identical power
spectrum solution excluded for 3 reasons:
1) h=0.57 2 from HST
2) worse fit SNIa results
3) poor fit 2dFGRS galaxy power spectrum surveys
!!!! WMAP note !!!!!
Blanchard et al. controversial
in Spergel et al., 2003 ApJS, 148, 175
C. Tao, Chamrousse 2004
h M
WMAP
CDM
Tegmark et al. astro-ph/0310723
Baryon fraction
M=0.4 h=0.72
=0.5 h=0.56
Indication for
- Systematics
- not cste w?
- ?
SDSS galaxies power spectrum
C. Tao, Chamrousse 2004
Precision cosmology? Not Just Yet
Bridle et al. Science 299(2003) 1532astro-ph 0303180
C. Tao, Chamrousse 2004
SNIa: fits with weak priorsM = 0.30 +/- 0.2
~ no prior on M (flat Universe), eg, M < 0.60
other solutions still possible : even decelerating Universes
Virey, Ealet, Tao, Tilquin, Bonissent, Fouchez, Taxil astro-ph/0407452
Quintessence
Phantom
C. Tao, Chamrousse 2004
SN data interpretation needs more precise determinations of Mor combination with other data
Tools needed for combined analysis
Attempts: Tegmark & Wang, Corasaniti et al., Padmanabhan et al.,…
For different models, eg, with variable w
Tools existing for each observation eg,
CMB: CMBFAST, etc…
SNIa: Kosmoshow, Y. Wang, …
Weak Lensing, Clusters, …
Extraction of cosmological parameters using « priors» on other data
C. Tao, Chamrousse 2004
Combined SN, CMB, WL constraints on equation of state
Upadhye , Ishak and Steinhardt, astro-ph 0411803
Future constraints
SNAP/JDEM + Planck
10% measurement
C. Tao, Chamrousse 2004
w is measurable by WL power spectrumBut degeneracy between w, M ,8 and
Dark Energy and Weak Lensing
Hui 1999, Benabed & Bernardeau 2001, Huterer 2001,Hu 2000, Munshi & Wang 2002
C. Tao, Chamrousse 2004
“Weak gravitational Lensing”
Background image distorsions by foreground matter
Without lensing lensing effect
Weak Lensing
jij
iij zgdz
2
)(
Direct measurement of mass distribution in the universe,
Other methods measure light distributions
Distortion Matrix :
C. Tao, Chamrousse 2004
“Weak Lensing”: principle
Distortion Matrix :
Convergence:
Shear:
Critical surface density:
221
crit
212221121
1 ;)(
lsol
oscrit DD
D
G
c
4
2
22
21
1
1
j
iij
Weak lensing regime : << 1 (linear approximation)Measure shear and solve for projected mass
C. Tao, Chamrousse 2004
Spectroscopy when possible
• SN Ia Identification
Spectrum structure
• Redshift z measurement
From position of identified lines from spectra SN and/or underlying galaxy
C. Tao, Chamrousse 2004
Supernovæ identification
Simulation of a SN Ia spectrum at z0,5
With Spectra
Main stamp of the SNe Ia: Si II at 6150 Å (supernova rest frame):
Hardly observable beyond z > 0.4-0.5.
Otherwise, search for features in the range 3500-5500 Å (supernova rest frame):
Ca H&K, SiII at 4100 Å, SII, …
Ca H&K SiII 4100
observed
at VLT
(SNLS)
C. Tao, Chamrousse 2004
SNIa sample contamination
Need strict selection criteria
But reduces statistics !
C. Tao, Chamrousse 2004
Atmospheric transmission (ground)
Reduction of transmission in visible Absorption water & O2 reduce visibility in IR
Reduced efficiencyNot homogeneous filtersRedshift dependent !!!
C. Tao, Chamrousse 2004
mmsz
arcmms
arcmms
///1050. :light maximumat SNIa 7.1
sec////1050. : Zodiacal
sec////10602 :Continuum
22
222
222
Atmospheric emission
C. Tao, Chamrousse 2004
Systematic effects
Extragalacticenvironment
Supernovaenvironment
reduction/correlationsSNIa contamination
Selection bias Inter calibration filters
local
Normal Dust absorptionLensingGrey DustSN evolution
C. Tao, Chamrousse 2004
Systematic effects
Astrophysical problems• 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
Observational problems
Standardisation method
Light curve fitting
Heterogeneity of SN data
SNIa identification
Subtractions
Calibrations
Atmospheric corrections
K-corrections
Selection bias
C. Tao, Chamrousse 2004
mag
SN Ia photometry needs many corrections
light curve
- Atmospheric observational corrections
- Light Curves measured in SN reference frame in local reference frame
- Galactic extinction correction
NOT ALL VERY PRECISE OR WELL UNDERSTOOD!, YET!
C. Tao, Chamrousse 2004
Precision on the magnitude dominated by intrinsic dispersion:mint 0.15
Stretch uncorrected
Stretch corrected
Precision on the magnitude at the maximum
C. Tao, Chamrousse 2004
Spectrum is dilated by (1+z) Flux is integrated in a filter for a photometric point, but filter responses are not flat.Sometimes, need different filters Corrections for differences ( shift) Systematic effects
Redshift calibration
C. Tao, Chamrousse 2004
Dependence on SN Environment
Blue have a lower metallicity - Can be seen further
C. Tao, Chamrousse 2004
Supernovae evolution
Sullivan et al (2002) SCP
SNIa host galaxy morphological classification
Not a large effect, but statistics are still low
Peak magnitude can change
Explosion changes with environment
Difference of chemical elements around SN
Depends on galaxy morphology, age, type,…
C. Tao, Chamrousse 2004
Extinction and Dust
• Extinction by dust from Our or SN galaxy
Rv=3.1 +/- 0.3 for our Galaxy Very large correction
Effective SNIa Rv~ 2 ?
• 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 ?
C. Tao, Chamrousse 2004
A strong limit on grey dust?
Peerels, Tells, Petric, Helfand (2003)
• 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
C. Tao, Chamrousse 2004
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? Need to go to z> 1
C. Tao, Chamrousse 2004
Gravitational Lensing in a Clumpy Universe
Weak lensing approximation:
Power spectrum of mass density in a relatively smooth universe
C. Tao, Chamrousse 2004
Systematic errors 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
C. Tao, Chamrousse 2004
A m=0.27 shift of low z data
Shift z <0.15 data by m= 0.27
m= 0.43 +/-0.2 and = 0 +/-0.34
Use Kosmoshow by A. Tilquin!
No need for
But Universe is not flat!
A « 2 » effect!
C. Tao, Chamrousse 2004
5) How can SN results be improved?
• Data still dominated by statistical errors Need more data Better study of systematic effects ground + space
• Study of w(z):
Need large sample of low z data for systematics
Need higher z data Need low z UV SN sample
need to go to space atmosphere
Need better quality data
Reduce atmospheric fluctuations
Gain statistics by spectro most SN
C. Tao, Chamrousse 2004
Requirements for SNIa search
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.
Best in space!
C. Tao, Chamrousse 2004
How to constrain 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
C. Tao, Chamrousse 2004
Low z activities
•Nearby SuperNova Factory
–300 SNIa (2004-…) snfactory.lbl.gov
•Physics of SNIa explosions
•Supernovae at CfA (ongoing…)
–Expect ~ 100
www.harvard.edu/cfa/oir/Research/supernova.html
C. Tao, Chamrousse 2004
Low z: Nearby Supernova Factory (2004-…)
Collaboration—France: CRAL,IPNL, LPNHE
—US: LBNL, U.Chicago
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)
C. Tao, Chamrousse 2004
Intermediate z (2003-2014)
• ESSENCE at CTIO www.ctio.noao.edu/wproject/sne
—~50 SN Ia/year
• SNLS with MEGACAM of CFHT Legacy Survey /snls.in2p3.fr/
— MEGACAM working since march 2003
— Foreseen : 700 SNIa z < 1.
C. Tao, Chamrousse 2004
SNLS : the instruments
A wide field camera (1 square degree, MEGACAM 0.35 Giga pixels) on 3.6 m CFHT (Hawaii) telescope
C. Tao, Chamrousse 2004
SNLS : expected results
contraint
contraint
SN only : ~0.1 and w~0.2
limited to z<0.95 (atmosphere)
C. Tao, Chamrousse 2004
Joint Dark Energy Constraints
Current efforts focus on the complementarity of
supernova and weak-lensing measurements of the
dark-energy parameters.
CFHTLS Wide Field: Weak Lensing - an ongoing program
C. Tao, Chamrousse 2004
What are the WL systematic limits and survey size that matches them??
Joint Dark Energy Constraints from SNAP
Dark Energy Constraints from “Cross-Correlation Cosmography”
Bernstein & Jain 2004
Constraints from Power Spectrum and Bispectrum
Takada & Jain 2003
(w´wa/2 at z=1)
NOTE: Lensing constraints do not
contain systematic error estimates.
C. Tao, Chamrousse 2004
SNAP /JDEM a dedicated satellite
Large statistics: 2000 Sne Ia/yr redshift to z<1.7, Minimal selection Ia identification
2m wide field telescope
C. Tao, Chamrousse 2004
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 observed ~4 daysAll images are accumulated
Observe repeatedly same
sky area
SNAP survey
Wide field !!
C. Tao, Chamrousse 2004
6) Testing the Dark Energy Paradigm
+ Theory !
Where is progress to come from?
+ Phenomenology
+ Observations
C. Tao, Chamrousse 2004
A Quantum Gravity effect?
- What is the average density of the Universe that is measured by cosmologists?
- If it has to do with Quantum Gravity Vacuum fluctuations, need to unify General Relativity and Gravity!
Loop Quantum Gravity
Ashtekar, Smolin, Rovelli,
etc…
SuperStrings
……..
Extensions to GR
Moffat
Negative energies
Henry-Couannier
MOND
Milgrom, Beckenstein
QFT in curved spacetime
C. Tao, Chamrousse 2004
Alternative views on Dark Energy
Sakharov (1968) Alternative views
gravitation is induced =/= fundamental interaction
<== fluctuations of quantum vacuum
Interpretation of G. Volovik (gr-qc/0304061)
The Universe in a Helium droplet, Clarendon Press, Oxford (2003)
Analogy superfluids 3He, 4He
Systems with Fermi and Bose quantum fields describing the interactions of elementary quasiparticles, with each other and with
the vacuum
C. Tao, Chamrousse 2004
Testing the Dark Energy Paradigm
+ Theory !
Where is progress to come from?
+ Phenomenology
+ What about testing Physics in the Lab?
+ Observations
C. Tao, Chamrousse 2004
Zero point energy and vacuum fluctuations
Planck’s second theory of black body radiationAverage energy of collection of oscillators
Zero point energy term
Experimental effects:
- X-ray scattering in solids
- Lamb shift understanding between s and p levels in hydrogen
- Casimir effect
- Origin of van der Waals forces
- Interpretation of Aharonov-Bohm effect
- Compton scattering
Look eg, @
Spectra of noise in electrical circuits
Well known black-body spectrum
C. Tao, Chamrousse 2004
Josephson junctions evidence for ZPE term
From Koch et al., Phys. Rev. B, 26, 74, (1982).
C. Tao, Chamrousse 2004
From Koch et al., Phys. Rev. B, 26, 74,(1982).
Possible cutoff?
Interesting lab experiments ?
A factor 3 to gain from 1982 experiment
TeraHz Josephson junctions ?
Exist in LERMA
C. Tao, Chamrousse 2004
DE Contributions cannot be determined from noise
measurementsJetzer & Straumann, astro-ph 0411034
The absolute value of the ZPE of a quantum mechanical system has no meaning
when gravitational coupling is ignored.
All that is measurable are
changes of the ZPE
under variations of system parameters
or of external changes
ZPE =/= Gravity vacuum fluctuations
C. Tao, Chamrousse 2004
Modern Cosmology: Dark Matter, Dark Energy
Modern epicycles?
Need for a conceptual Revolution?
C. Tao, Chamrousse 2004
A mysterious and interesting Universe
Ordinary Matter: 4%
Definition: c (c=10-29 g/cm3)
2/3
Dark Energy?
1/3 Dark Matter?
CMB, + SN, clusters, galaxies redshift surveys, Weak Lensing, …
Concordant CDM model with
Cold Dark Matter and Cosmological constant ???
WMAP
Position 1st peak =1.02 +/- 0.02Flat universe
Ratio (2/1) peaksB =0.046 +/- 0.006
Ordinary Matter: 4%