Connecting fundamental physics with observations, KITPC, 2009 1 Observational windows of cosmological physics 张鹏杰（ Zhang, Pengjie) 中国科学院上海天文台 Shanghai

Connecting fundamental physics with observations, KITPC, 2009

1

Observational windows of cosmological physics

张鹏杰（ Zhang, Pengjie)

中国科学院上海天文台Shanghai Astronomical Observatory

Chinese Academy of Science


2

The dark universe

The visible world

The dark universe•Dark matter?•Dark energy?•Modified gravity?•Violation of EP, Lorentz invariance?

•Violation of Corpernican Principle?


3

Windows to the dark universe

z ~ 1000 z ~ 30 z ~ 6 z ~ 0z ~ 1000 z ~ 30 z ~ 6 z ~ 0z ~ 1000 z ~ 30 z ~ 6 z ~ 0

21cmSoon to detect


4

General relativity and GR tests

General principle of relativity

Equivalence principle

Field equation

Confirmed at 10^(-13)

Gen

eral covarian

ceT

enso

r analysis

perihelion shiftlight deflectiontime dilation/frequency shiftorbital decay (gravitational wave)time delaygeodetic effect?frame dragging effect

(e.g. 5

2 2 1 2 2

1 10

2 2(1 ) (1 )

GM GMds dt dr r d

r r

－＝

：


5

GR and cosmology: dark matter

Density fluctuations in baryons are ~10^-5 at ~100 Mpc/h at z~1100

Density fluctuations today are ~0.1 at 100 Mpc/h

If only baryons and photons exist, density fluctuationstoday <10^-2. Even worse at smaller scales

So dark matter must exist, whose rms fluctuation must be orders of magnitude larger than that in baryons at CMB epoch!

X


6

GR and modern cosmology: non-zero cosmological constant

• Cosmic acceleration– DL-z relation from cosmic

standard candles SNe Ia, 1998-

• Decay of gravitational potential (the Integrated Sachs-Wolfe effect)

2003-

Riess et al. 2005


7

The story of the Vulcan planetNewtonian gravity predicts the Mercury orbit to be closed (if Sun+Mercury only)

Observations found that the Mercury orbit is not closed and the perihelion procession is 43 arcsec/century

Theory conflicts with observation→New mass? Flaw in Newtonian gravity?Le Verrier (the one predicted Neptune) postulated the planet VulcanWe now know Vulcan does not exist and instead, Newtonian gravity goes wrong


8

Modifications in particle physics

Modifications in general relativity

Theories beyond the GR (with non-zero cc)+DM LCDM cosmology

Dark matterWIMPAxionetc

MG replacing DMMOND (TeVeS)etc

Unified DM/DEDM/DE interaction

Unified MG

Dark energyQuintessencePhantomQuintometc

MG replacing DEDGPf(R)etc

Cosmological consequences

Expansion Well understood Partly understood

Linear perturbation Almost well understood Partly understood

Nonlinear evolution(simulations and/orsemi-analytical cal.)

Almost well understood for smooth DEPreliminary for clustered DE

Big progress, but still preliminary


9

To describe the universe

• Zero order (The overall expansion and geometry)

• First order (The large scale structure)

(5)( ), , ,.. , , , ( )....L A m DE DE PlanckH z D D w M DGP

, , , .. .... , , , ....s effv c G

for dark energy

Modified gravity

3

83

8

2

2

G

r

HH

GH

c

eff2

2

G4

G4

example: H inflat CDM and DGP


10

Probes of the expansion

• Type Ia supernovae (standard candles)

• Baryon acoustic oscillation in LSS and CMB (standard ruler)

• Fundamental plane, Faber-Jackson & Tully-Fisher of galaxies• Age (globular clusters, galaxy age-z..)• Gravitational lensing time delay• SZ-X ray cluster fluxes• Cluster gas fraction• Gamma ray bursts• Alcock-Paczynski (AP) test• .....


11

Expansion rate to test gravity

Song et al. 2006

3

83

8

2

2

G

r

HH

GH

c

reminder: H inflat CDM and DGP

DPG is disfavored comparing to LCDM

Stage IV: SNAP, LSST, etc. thousands well calibrated SNe Iasub-1% accuracy in DL


12

Baryon acoustic oscillations as cosmological standard rulers

Eisenstein, et al. 2005

astro-ph/0501171

tell us the distance

tell us the distanceand H(z)


13

BAO:clean physicsmeasures both D(z) and H(z)Stage IV projects: SKA, ADEPT, HSHS,etc. Can reach sub-1% accuracy

Blake et al. 2006


14

Some near and far future probes

• Near future– Water maser orbital motion measurement

• Far future– Gravitational wave of black hole binaries– Sandage-Loeb test (temporal shift in Lyman-al

pha absorption lines)

Connecting fundamental physics with observations, KITPC, 2009 15

Water maser: a semi-absolute distance indicator

Barvainis & Antonucci, astro-ph/0506245

water maser

Observing these water maser cloud for years to measure the proper motion and acceleration


Water maser: a semi-absolute distance indicator

astro-ph/9907013


Sandage-Loeb test

Observe the lines for decades and measure motion against time

A measure on H

0 (1 ) ( )zH z H z

t

observables

A. Sandage, Astrophys. J. 139, 319 (1962).

A. Loeb, Astrophys. J. 499, L111 (1998), [astro-ph/9802122].

Lyman-alpha absorption (Lyman-alpha forest)


Corasaniti et al., arXiv:astro-ph/0701433v1

Unique tool to measure H(z) at z~3


Standard Sirens: gravitational waves from SMBBH and short GRB (e.g. Hughes & Holz, 2003; Dalal et al. 2006)

Gravitational wave of binaries can be used for self-calibrated precision distance measurement (Challenge: position?)

Short GRB: can be well localized

Low z GRB will fix H0

High z SMBBH: measure w

GRB 050509bThe first short GRB been located

SMBBH detected byChandra


Hughes and Holz astro-ph/0212218

Dalal et al. astro-ph/0601275

SMBBH

Solar mass BBH


21

CMB: DSN: D

BAO: D,H 21cm BAO: D, H

maser: D

GW: D GW SMBBH: D

SL: H

redshift

0 1 2 6 50 1100

expansionprobes

cluster: fgas, SZ/X-ray: D

weak lensing: D

GRB: D


22

Probes of the large scale structureThey may not probe what we think that they probe!!

• gravitational potentials– Gravitational lensing– Galaxy/cluster peculiar velocities– The integrated Sachs-Wolfe effect

• density– galaxy clustering– cluster abundance

• fluid velocity– The kinetic Sunyaev Zel'dovich effect?

－.

v ( )

d

dt

g gb

(1 )p v

Refer to Jain & ZPJ, 2008, PRDfor details

??


23

Gravitational lensing

Distortion in galaxy shape （ cosmic shear)

Sophisticated method

Change in galaxy number density （ cosmic magnification)

Detected

Anisotropies and non-Gaussianity in cosmic backgrounds (CMB, 21cm, etc.)

Preliminary detection in WMAP


24

How to do precision lensing measurement• Cosmic shear (by far the most sophiscated)

– Even with galaxy disk orientation measurement! (Morales, 2007 arXiv:astro-ph/0608494)

• Lensing of cosmic backgrounds

– CMB lensing • Seljak & Zaldarriaga, Zaldarriaga & Seljak 1998;Hu & Oakamoto 2002

– 21 cm background lensing • Cooray 2004; Pen 2004; Zahn & Zaldarriaga 2006; Mandel & Zaldarriaga 200

6; But non-Gaussianity!

• Lensing magnification in flux– Ia supernovae

• Cooray et al. 2006; Dodelson & Vallinotto 2006; but see ZPJ & Corasaniti 2007

– Galaxy fundamental plane• Bertin & Lombard 2006; but see ZPJ & Corasaniti 2007

• Cosmic magnification (lensing induced galaxy density fluctuations)– Magnification-galaxy (Scrantan et al. 2005)

– Magnification-magnification• ZPJ & Pen 2005, 2006 (find ways to eliminate galaxy clustering and thus enables

the lensing-lensing measurement)


25

CMB vs. Lensing

Primary CMB Weak LensingPrecision measurements: WMAP, PLANCK, CMB-Pol, etc.

Precision measurements: CFHTLS, DES, SNAP, LSST, Pan-STARRS, SKA, Euclid,etc.

Robust theory baryon+lepton physics

Linear, Gaussian

Accuracy: better than 1%

Robust theory:

Gravity

Nonlinear, Non-Gaussian N-body simulations (+hydro)

Information:

Cl (l<3000)

zcmb =1100 ---2D

Information:

Cl (l<~104), B(l1,l2,l3), etc.

z=1100, 10, 5-0 ----3D


COSMOS-3D lensing－》 3D distribution of dark matter

Lensing tomography


27

Weak lensing and cosmological applications

22 2 2( , ) ( , ) ( , )

2

sourcel

i L S LL Lobserver

l C l lk z D k z W x x dz

l x x

lensing power spectrum: observable

Linear power spectrum: probes primordial fluctuations and tests inflation

Nonlinear structure growth rate. Probes DM, DE, gravity and neutrino mass,

Lensing kernel: tells us the distance-redshift relation and the curvature of the universe

Refregier 2003Schneider 2005Munshi et al. 2006Hoekstra & Jain 2008


28

CFHTLS:i band, 57deg2 Fu et al. 2007

also, Hoekstra et al. 2005

Eventually,5 bands,170 deg2

B mode: Measure of systematics

Great progress!

Cosmic shear has been measured robustly!


29

• Stage IV: LSST, SKA, Euclid, etc. • ~20000 deg^2• billions galaxies• sub-1% in power spectrum


The dark energy task force recommends fourprobes of the expansion: SN and BAOprobes of structure growth: weak lensing and cluster abundance

Figure of merit for stage IV space projects

Peculiar velocity as the fifth!!

Part 2


31

Distinguishing DE/MG: (1) Global fit

Fang et al. 2008 H. Zhang et al. 2008

LCDM

DGPDGP is less favored, or even ruled out


32

Weak lensing/LSS and Yukawa-like gravity

Dore et al. 2007arXiv:0712.1599


33

For future data,Zhao et al. 2008


34

• Independent methods to measure the distances.– D(EM): from EM waves

(SN, BAO, maser, etc) – D(GW): from gravitationa

l waves (GW)

• If gravity is GR in 4D, then D(GW)=D(EM)

• Otherwise, interesting things can happen– Example: if GW can leak

into the 5th dimension,

– D(GW)>D(EM)

Deffayet & Menou, 2007

D(EM)

D(GW)

Distinguishing DE/MG: (2) Smoking guns


35

To test gravity, we need to break the dark degeneracy I:

MG and DE can mimic each other exactly in H(z)

13 (1 ) /2 2 3 2

0 0( )DE

aw da a

DE kH H a e a

2 3 2 '0

0

[ln( )]3

/

DE k

aw E a a

E H H

produced by any model

There are always dark energy models with degenerate H!

To distinguish between DE and MG, one must have LSS,besides the overall expansion of the universe!


36

Consistency check of GR at cosmological scales

02

33/32

200

22

2

aH

H

aaH

dadH

da

d

da

d

The expansion rateThe rate of

structure growthConsistency relation

observables


37

Consistency check of GR: Real data!!

Wang et al. 2007 arXiv:0705.0165

Consistent with GR

Expansion

structure growth


38

Wait a second

Wang et al. 2007 arXiv:0705.0165

Expansion

structure growth

Sign for MG?Sign for nothing?


39

Ishak et al. 2005

Also Knox et al. 2005

Underlying gravity:5D braneworld

DGP

Fit with GR

Future surveys can do much better


40

It is possible for a dark energy model to reproduce gravitational lensing and matter density fluctuations in DGP(Kunz & Sapone 2006)

Kunz & Sapone 2006

See also Bashinsky 2007Hu & Sawichi 2007

Two extra degrees of freedom in dark energy models

•the anisotropic stress•pressure fluctuations

Two extra degrees of freedom in modified gravity models

•Newton's constant•relation between two potentials

We need multiple probes of LSS to break the dark degeneracy II: modifications in gravity and DE/DM may mimic each other in some LSS


41

Linear level large scale structure (LSS) in LCDM ， general dark energy models and modified gravity models.

4 perturbation variables: δ,v: perturbations in fluidΦ,ψ: perturbations in space-time

Ma & Bertschinger 1995Hu & Eisenstein 1999 ZPJ et al. 2007

Amendola et al. 2007

Holds for LCDM, DGP, f(R), Yukawa, etc.Extra perturbations in MOND scalar and vector fields


42

If 3 or more independent LSS variables can be measured, modified gravity models can be unambiguously discriminated from DE/DM

Jain & ZPJ, 2008

Break the dark degeneracy II

One necessary condition for DE to mimic MG


43

In the afternoon, I will talk about

• Large scale peculiar velocity as a probe of gravity

• Testing the Copernican principle


44

Part 2Peculiar velocity: a window to the dark universe

• Matter distribution in our universe is inhomogeneous

• Gravitational attraction arising from inhomogeneity perturbs galaxies and causes deviation from the Hubble flow

v

r

v

r

peculiarvelocity

v=Hr v=Hr


45

http://www.astr.ua.edu/keel/galaxies/distance.html


46

What makes peculiar velocity special and important to probe gravity?

At scales larger than galaxy clusters, only respond to gravity

In linear regime, honest tracer of matter distribution

Necessary for the complete phase-space description of the universe

dt

vd

dt

av)d（

01

vadt

d


47

GREAT attractor(s), with far more mass than expected, must exist in order to pull the Milky way at ～ 600 km/s with respect to CMBSuch gigantic structures should be no coincidence, if we believe in the cosmological principle

Great attractor

Shapely concentration

Early applications of peculiar velocity: (1) A brave new world with gigantic structures


48

Early applications of peculiar velocity: (2) road to the standard LCDM cosmology

• Largely based on peculiar velocity measurements of local and nearby galaxies, some cosmologists (e.g. Jim Peebles) argued that the the cosmological constant may exist and account for ~80% of the energy budget of the universe, in early 80s.


49

How to measure peculiar velocity?Traditional method

v

r

Subtract the Hubble flow to obtain the peculiar velocity

v=Hr

Measure the recession velocity from the redshift

Measure the distance through FP,TF,FJ,SN, etc.


50

• A factor of 3 larger than the LCDM prediction

• Not so right asymptotic behaviour

Watkins et al. 2008


51

CMB photonfree electron

scattered CMB photon

pgksz vMS

vp: bulk velocityscattering probability

The kinetic Sunyaev Zel'dovich effect

Recently, the South Pole Telescope (SPT) has for the first time discovered clusters, through the thermal SZ effect!


52

Constraints of velocity from cluster kinetic SZ effect


53

Measuring velocity from KSZ

Allows statistical measurement of vp (vp power spectrum)

Measure vp of individual clusters

• Requires other measurements to infer Mg

– Thermal SZ to have MgT– X-ray to have T

ZPJ et al. 2008

pgksz vMS

Haehnelt & Tegmark 1996;Kashlinsky & Atrio-Barandela 2000; Aghanim et al.2001; Atrio-Barandela et al. 2004; Holder 2004


54

SNe Ia as speed censors

F

F

cz

V

Peculiar velocity causes fluctuations in SNe Ia flux

Noisy, but feasible. Already allow velocity measurement at z<0.1

Wang, Lifan. 2007


55

SNe Ia as cosmic speed censors at intermediate redshift ~0.5

ZPJ & Chen, 2008

At z>0.1, lensing dominates over velocity

Measure the 3D power spectrum ofSNe Ia flux, in which noise can be significantly suppressed

signal (velocity)

Noise (lensing)

z=0.5


56

)()1)(()( 22

H

kuFukPkP g

sg

)(ln

ln ; z

ad

Ddf

b

fm

g

Redshift distortion and cosmology

Peacock et al. 2001

Kaiser effectinduced by large scale coherent infall

Finger of Godinduced by small scale random motion


57

A sensitive measure of gravity

Guzzo et al. 2008

Acquaviva et al. 2008

Spectroscopic redshift surveys•Measure beta from the anisotropy•Measure galaxy bias•Obtain f

Current measurements


58

Spectroscopic redshift surveys measure (1) the expansion from BAO and(2) the growth rate from redshift distortion

Amendola, Quercellini &Giallongo 2004

BAO

BAO+RD

RD helps to improve dark energy constraintsHowever, the improvementis not significant for future big surveysBecause if smooth dark energy, BAO and RD basically probes the same H(z)


59

Strong tests on gravity

Yun Wang 2007See also Eric Linder 2007

DE and MG can have nearly degenerate H(z)

But their structure growthrate can be very different


60

Testing the consistency relation through spectroscopic redshift surveys

Acquaviva et al. 2008

=0 in GR+smooth dark energy

BAO

Redshift distortion


61

Layers of assumptions/approximations

2 412( , ) ( 2 ..) ( )s

g g gv vP k u P u P u P F ku

2 412( , ) ( 2 ) ( )s

g g gv vP k u P u P u P F ku

e.g. Matsubara 2007

e.g. Tegmark et al. 2002,2004Scoccimarro 2004ZPJ et al. 2007, ZPJ 2008

deterministic bias

e.g. Peacock et al. 2001;Guzzo et al. 2008;Amendola et al. 2004Linder 2007;Wang 2007More uncertainties:

•Linear evolution•Light cone•distant observer assumption•.....

F: Lorentz or Gaussian

2 212( , ) (1 ) ( ) ( )s

g gP k u u P k F ku

scale independent galaxy bias

e.g. Acquaviva et al. 2008


62

On real data

• Tegmark et al. 2002 on 2dF

• Tegmark et al. 2004, on SDSS

One can measure the gg,gv,vv power spectra simultaneously.

errors (vv)>errors(gv)>errors(gg)


63

Forecast for future surveys the Square Kilometer Array (SKA) as an example

Future surveys can detect (1) stochasticity in galaxy bias (2) scale dependence in galaxy bias

We are no longer able to use the usual Kaiser formula.

At such stage, more detailed check against current RD model and/or more accurate RD modeling are required

ZPJ 2008

SKA, ADEPT, HSHS will map more than half the sky with accurate redshiftmeasurements.Ideal for BAO and RD study


64

V NewtonG

MG parameterization

effG

equivalentX X

~

1

~

~ ~

( ) gravity:

DGP gravity: 1

TeVeS: ( ,other fields)

R

Geff f

eff

eff eff uv

f R G

G

G G g

2DE: ( ) 12 (1 )

DGP: = (z) 1

k G w

Amendola et al. 2007Bertschinger& Zukin. 2008Caldwell et al. 2007Hu & Sawicki 2007Jain & ZPJ 2008Uzan 2006ZPJ et al. 2007


65

Testing the (generalized) Poisson Equation

)d 2s＝（－）W( ,

2 ( ) 8 G

=

Gravitational lensing

v H

f

fH

/

from peculiar velocity

?

Galaxy redshifts to recover redshift information (2D ->3D)


66

Weak lensingCosmic shear

DES, LSST, SNAP, DUNE, SKA, etc.Cosmic magnification

SKACosmic microwave and 21cm backgrounds

Large scale peculiar velocities (bulk flows)Galaxy redshift distortion from spectroscopic redshi

ft surveysStage III: LAMOST, BOSS, etc.Stage IV: ADEPT, Euclid, HSHS, SKA, etc.

Other methods (KSZ, SNe Ia, distance indicators .... )


67

A discriminating probe of gravity

•No dependence on galaxy bias

•No dependence on the shape and amplitude of the matter power spectrum, in the linear regime

•Scale independent in LCDM and QCDM, whose amplitude is completely fixed by the expansion rate

•Contains smoking guns of modifications in gravity and particle physics•Changes in the amplitude•Violation of the scale independence

22

( ) ( ) 1gG

g

PE

P

Poisson equation!

Linear density growth rate

galaxy-galaxy lensing

redshift distortion

f


68

LCDMf(R)DGPMOND

ZPJ, Liguori, Bean & Dodelson2007

• EG will be measured to 1% level accuracy within two decades

• Promising to detect one percent level deviation from general relativity+canonical dark energy model (if systematics can be controlled)!


69

One can further construct an estimator of η≡-Φ/ΨLensing: Φ-Ψ; Peculiar velocity: Ψ

ZPJ et al. 2008

Velocity measurement forecasted for SKA

?


70

ZPJ et al. 2008

•eta can be measured to 10% accuracy.

•Errors in eta is larger than errors in E_G•Even so, eta can have stronger discriminating power, in some cases.

•η of DGP differs significantly from that of LCDM. (EG of DGP is very close to that of LCDM.)

•eta and E_G are complementary

•DGP with high Omega_m

SKA forecast

DGP

MONDTeVeS

dark energy with anisotropic stress


71

The above argument is based on the cosmological principle, which is based on the belief of t

he Copernican principle

Our universe has no center ->homogeneous– The cosmological principle: our universe is homogeneou

s and isotropic. Described by the FRW metricViolation of this principle and cosmological conseque

nces– Dark energy as an illusion


72

void

The LTB universe

Lemaitre-Tolman-Bondi model– The universe is onion-like

If – we happen to live at the center

– surrounded by a huge Gpc scale void,

then – SNe Ia become dimmer than wha

t expected in FRW!

Violation of the Copernican principle fools us to accept cosmic acceleration, dark energy or modified gravity!


73

Dark matter, dark energy?

Modified gravity?

LTB with gigantic void in the center? Violation of the Copernican principle?

.....


74

Testing the Copernican principle From CMB observations, we

know that our universe is isotropic to us. Both FRW and LTB are acceptable.

How to know the universe viewed from other positions? Incomplete list of novel ideas:

– Reflecting mirrors and non-Blackbody spectrum (Caldwell & Stebbins 2008)

– Speeding clusters (Garcia-Bellido & Haugboue 2008)

– Distorted BAO (Clarkson, Bassett & Lu 2007, Zebin et al. 2008)

– Constant curvature condition (Clarkson, Bassett & Lu 2007); Time drifting in the cosmic past (Uzan et al. 2008)

– Slope of low z SN Ia distance moduli. (Clifton, Ferreira & Land 2008)

– Small scale CMB (Clifton, Ferreira & Zuntz 2009)

– Cosmic neutrino background (Jia & Zhang 2008)


75

2008 ， PRLarxiv:0711.3459

Ionized universe is a mirror to reflect CMB photons in other regions of the universe to usand thus tells us deviationfrom the Copernican principle

Deviation from the blackbody


76

Moving mirrors: the kinetic Sunyaev Zel'dovich effect

Dust (matter) comoving frame

Violation of the Copernican principle

Violation to the Copernican principle causes the relative motion between the CMB frame and the matter frame

Moving mirror causes the kinetic Sunyaev Zel'dovich effect

prediction

observations

CMB frame

In a homogeneous universe, no motion between the two


77


78

Initial condition of the universe

Physical principles

The universe

Nature of gravity, matter

and energy

Is the universe we observea fair sample of THE

UNIVERSE?

the cosmological principle

Nearly flat andhomogeneous?

Almost no defects? Adiabatic, Gaussian,

nearly scale invariant fluctuations?

single field Inflation

? ???

The dark universe: nothing is impossible

Bianchi?LTB?

cosmicstring?multi-field?

Gastrophysics?Nonlinearity?Backreaction?


79

lensing

SNe Ia

BAOcluster abundance

peculiar velocity

CMBWe are able to put everything together to reconstruct the elephant!

the dark universe

Documents

Connecting fundamental physics with observations, KITPC, 2009 1 Observational windows of cosmological physics 张鹏杰 （ Zhang, Pengjie) 中国科学院上海天文台 Shanghai

Connecting fundamental physics with observations, KITPC, 2009 1 Observational windows of cosmological physics 张鹏杰（ Zhang, Pengjie) 中国科学院上海天文台 Shanghai