Comments and Questions about the Dark Universe

C. Tao, Chamrousse 2004

Comments and Questions about the

Dark Universe

Charling TAO

CPPM & Université de la Méditerranée

Chamrousse, Dec. 2004

[email protected]


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


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


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 !


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


Supernovae: explosions

Core Collapse SN

SNIa : 2 stars (a white dwarf +…)

Red giant

White dwarf

Chandrasekhar mass 1.4 MO


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


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


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


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


SN are not exact standard candles!

The light of SNIa explosions can be followed up for several weeks with telescopes


Different standardisation methods

Before: mB After, eg, stretch correction: mBcor = mB – (s-1)

Different standardisation methods : stretch (SCP), MLC2k2 (HiZ), m15, ...


data analysis physics

The « classical » method

Images

Spectra

+ identification.

Ia

magnitude z(redshift)

galaxy

Hubble


Fit cosmological parameters

• From Hubble diagram, fit models

• Determine dark energy parameters , or (X, w, w’) and matter density M

z 1

mag


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


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


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


Riess et al. (fit quality)


Determination of Cosmological parameters

Riess et al, astro-ph 0402512

w=p/

w= w0+w’ z


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


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!


Riess 2004, gold sampleFit with no prior

Riess

CDM concordant model


• 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…


•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 ???


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


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


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


2dfGRS: use of CMB prior


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


Precision cosmology? Not Just Yet

Bridle et al. Science 299(2003) 1532astro-ph 0303180


Bridle et al.


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


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


Combined SN, CMB, WL constraints on equation of state

Upadhye , Ishak and Steinhardt, astro-ph 0411803

Future constraints

SNAP/JDEM + Planck

10% measurement


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


“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 :


“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


4) A closer look at SN measurements


Spectroscopy when possible

• SN Ia Identification

Spectrum structure

• Redshift z measurement

From position of identified lines from spectra SN and/or underlying galaxy


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)


SNIa sample contamination

Need strict selection criteria

But reduces statistics !


Atmospheric transmission (ground)

Reduction of transmission in visible Absorption water & O2 reduce visibility in IR

Reduced efficiencyNot homogeneous filtersRedshift dependent !!!


mmsz

arcmms

arcmms

///1050. :light maximumat SNIa 7.1

sec////1050. : Zodiacal

sec////10602 :Continuum

22

222

222

Atmospheric emission


Spectroscopy : Need to subtract galaxy


Systematic effects

Extragalacticenvironment

Supernovaenvironment

reduction/correlationsSNIa contamination

Selection bias Inter calibration filters

local

Normal Dust absorptionLensingGrey DustSN evolution


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


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!


Precision on the magnitude dominated by intrinsic dispersion:mint 0.15

Stretch uncorrected

Stretch corrected

Precision on the magnitude at the maximum


Knop et al (2003) light curves


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


Dependence on SN Environment

Blue have a lower metallicity - Can be seen further


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,…


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 ?


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


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


Gravitational Lensing in a Clumpy Universe

Weak lensing approximation:

Power spectrum of mass density in a relatively smooth universe


Some estimates of Systematics


Effect of de/amplification

Systematics for well identified SNIa


Systematic differences between standardisation methods (Riess et al.)


Constraints on cosmological parameters

m= 0.2 - 0.3 effect!


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


Riess gold sample sensitivity

Kosmoshow, A. Tilquin


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!


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


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!


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


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


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)


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.


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


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


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


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.


SNAP /JDEM a dedicated satellite

Large statistics: 2000 Sne Ia/yr redshift to z<1.7, Minimal selection Ia identification

2m wide field telescope


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 !!


Résultats-diagramme de Hubble SNAP Expectations


SNAP expected results

Weak Lensing + CMB


6) Testing the Dark Energy Paradigm

+ Theory !

Where is progress to come from?

+ Phenomenology

+ Observations


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


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


Testing the Dark Energy Paradigm

+ Theory !

Where is progress to come from?

+ Phenomenology

+ What about testing Physics in the Lab?

+ Observations


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


Josephson junctions evidence for ZPE term

From Koch et al., Phys. Rev. B, 26, 74, (1982).


Dark energy cutoff?

Beck and Mackey astro-ph/0406504


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


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


Modern Cosmology: Dark Matter, Dark Energy

Modern epicycles?

Need for a conceptual Revolution?


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%


Different types of Supernovae: Identification with colours

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