Recent Topics on Observational Recent Topics on Observational CosmologyCosmology

Naoshi Sugiyama

Division of Theoretical Astrophysics

National Astronomical Observatory, Japan

1. Introduction2. Cosmological Parameters3. Dark Matter4. Structure Formation5. Success of -CDM

§1.Introduction

-Observational Cosmology-Observe the features of the present and past Universe•Contents

baryon, electron, photon, neutrino

dark matter = unknown particles?, MACHO?•Cosmological Parameter

, H0, q0, , age dynamics

•Structure

galaxies, cluster of galaxies, Large Scale Structure

Cosmic Microwave Background

Extrapolate to the early Universe &

future Universe

•How was the Universe formed?

•What is the final fate of the Universe?

From the beginning to the end of the Universe based on observations

Observations by HST key project

must determine distance to measure H0

Cepheid Variables by HST

calibrate 0-point of various methods < 25Mpc, 27gal

(1) Tully-Fisher relation for spiral galaxies

rotational vel. v vs absolute luminosity L

v = 220(L/L*)0.22 km/s

line width W

§2.Cosmological Parameters(1)Hubble Constant H0

Sakai et al.astro-ph/9909269

(2) Fundamental plane of elliptical galaxies

velocity dispersion , radius r, surface brightness I

r 1.33 i -0.83 Oegerle & Hoessel 91

(3) Super Nova(SN)

light curve shape vs abs. luminosity

(4) Surface Brightness Fluctuations

flux: I=Nf (N: # of stars, f: flux of a star)

fluctuation: =N1/2f

2/I=f L/d (L:luminosity, d:distance)

Combine (Mould ApJ. 529 (00)786)

Cephaid distanceRiess, Press, Kirshner ApJ.473(96)88

HST Key ProjectFerrarese et al.astro-ph/9909134

Tully-Fisher: red, SNIa: green, SBF: blue, Fundamental plane: cyan Ferrares et al. astro-ph/9909134

km/s/Mpc8720 H

The biggest uncertainty is from distance to LMC

=> determine the 0 point of Cepheide

Freedman et al. ApJ, astro-ph/0012376

They assume

dLMC=50±3kpc

Other estimator of Cepheid 0 point

NGC 4258

7.2±0.3Mpc: orbital motion of disk

Herrnstein et al. Nature 400, 539 (99)

8.1±0.4Mpc: CepheidMaoz et al. Nature 401, 351 (99)

=> Cepheid has 12% error?

dLMC=44kpc? H0=80km/s/Mpc?

The devil is in the distanceThe devil is in the distance ©Bohdan Paczynski

(2)Cosmic Age t0

Cosmic Age Crisis?

t0=2/3H0=8.1(0.8/h)Gyr. for M =1, =0

=1/H0=12(0.8/h)Gyr. for M =0 , =0

H0=100h[km/s/Mpc]

•measurement of cosmic age

HR diagram of Globular Cluster

t0 > tGC = 11 ±1.0±1.4Gyr Cassisi et al. A&AS134(1999)103

= 13 ±2Gyr Chaboyer, talk given in Feb. 2001

high metal

low metal

Universe must be almost empty or

dominated by cosmological constant

Cutoff in White Dwarf Luminosity Function

t0 > tdisk = 10.5 (+2.5-1.5) Oswalt et al. Nature382(1996)692

(3)Cosmological Constant

High z Super Novae Ia Search

luminosity distance 02

0 /])1()[1( HzqzzdL

q0 : deceleration parameter

If we measure the distance to high z objects, we can determine q0 or /3H0

2

Perlmutter et al. ApJ.517 (99) 565

42 galaxies 0.18<z<0.83 2/ M 0 q

1.02.06.08.0 M

Two Loopholes:

•evolution of SN Ia

Are SNe at z~1 same as at z=0?

•Extinction by dust

light from SN may suffer significant damping by interstellar dust

Cosmology and these systematic can be

distinguished if once we see SNe at z>1

Discovory of SNIa at z~1.7

SN 1997ff: photometrical redshift of SN, z=1.70.1

Gal, z=1.650.15

Riess et al. astro-ph/0104455

M 1/3 2/3

SNAP(Supernova/Acceleration Probe)

2000 SNe/yr. 3yr. 0.1<z<1.7

(4)Curvature of the Universe KMK=1 (Friedmann eq.)K-/(a0 H0)2

CMB anisotropies

Measure the Last Scattering Surface (LSS) (z=1000)

Projection from size on LSS to angle

•Observable quantites: Cl

angular power spectrum

l: multipole 1/

•Peak location of Cl :

corresponds to sound horizon

Observer

Last Scattering

Flat Universe

三角形の内角の和 180 度Open Universe

内角の和＜ 180 度

Closed Universe

内角の和＞ 180 度

Observer

Observer

l1/

Peak shifts to larger l (open)

smaller l (closed)

Small scaleLarge Scale

Not only curvature BUT also

• Bh2

• Mh2

• n (initial power law index)

• T/S (tensor perturbation contribution)

• reionization after recombination

Boomerang(Balloon) caltech, USSB, Rome

•long duration balloon: over 10 days

altitude 35km, 1milion m3 balloon

multi band: 90, 150, 240, 400GHz

•bolometric detectors cooled to 0.3K

•high resolution: 18’, 10.5’, 14’, 13’

•high sensitivity: 140, 170, 210, 2700Ks1/2

•256hours data, 2.5% of skyP.de Bernardls et al. Nature 404 (2000)955

A.Langee et al. astro-ph/0005004

•Peak location llpeakpeak=197±6=197±6 (1 error)

c.f. 220 for adiabatic std 220 for adiabatic std =1 CDM=1 CDM

Flat CDM

with (SNe Ia)

0.88< 0.88< mm++ <1.12 <1.12

(95%CL)(95%CL)6 parameters fit

m(0.05-2), (0-1),h(0.5-0.8), n(0.8-1.3)

Bh2(0.013-0.025)

MAXIMA-I (Balloon) UCB, Minnesota

•balloon: 3 hours (2 orders worse)

•multi band: 150, 240, 410GHz

•bolometric detectors cooled to 0.1K (factor 3 better)

•high resolution: 10’

•high sensitivity: 80Ks1/2 (factor 2 better)

Confirm BOOMERANG resultConfirm BOOMERANG result

Jaffe et al.

Astro-ph/0007333

More data coming on April 2001

• Boomerang reanalysis (astro-ph/0104460)

• MAXIMA reanalysis (astro-ph/0104459)

• DASI: interferometer at south pole (astro-ph/0104489)

Consistent with Flat, BBN Bh2 (=0.022) CDM model

§3.Dark Matter

(1) Matter Density 0 (M)

重力的に測定する必要

光っている成分：　 ＊ = 0.004

Scale によって違い：　 Large scale ほど大きい

(a) 銀河の flat rotation curve

flat rotation curve suggests the existence of

Dark Halo Component = Dark Matter Begman, Broeils, Sanders MNRAS 249,523 (1991)

halo

diskgas

(b) スケール依存性

N.Bhacall

astro-ph/9901076

(2) Baryon Density B

•Takes place at T=1010 ~ 109K

•Function of baryon-photon number ratio

nB/n=2.68 10-8Bh2

これが大きいと反応早めに進む

n が p への崩壊が進んでいなかった

n が増え、結果 4He の量が増える

D, 3He は燃えかすなので、少なくなってしまう

Big Bang Nucleosynthesis

Review: Tytler et al. astro-ph/0001318

反応の時間発展

理論値と

観測値

Bh2 = 0.019±

0.0024(95%)

h=0.65

D の Ly-

Recent results of D-abundance

Pettini & Bowen astro-ph/0104474

QSO 2206-199

D/H=(1.65±0.35)10-5 very low value

D/H=(2.2±0.2)10-5

3 Damped Lyman Alpha system (higher column density) out of 6 measurements of D/H

Bh2 = 0.025±0.001(1)

B << M

Non-Baryonic Dark Matter の存在！

(3) Dark Matter の候補

（ A) 素粒子論的候補

粒子の持つ運動エネルギーで分類

a) Cold Dark Matter (CDM)

熱浴から早い時期に離脱し運動エネルギー小

候補粒子

• 最も軽い超対称粒子 (LSP)

• axion

Weakly Interacting Massive Particles (WIMPs)

いまだかつて見つかっていない

b) Hot Dark Matter (HDM)

熱浴からの離脱遅く、運動エネルギー小

候補粒子

• 質量のあるニュートリノ

必要な質量は super-Kamiokande の値より

はるかに大きい2eV]84.93/3[ hm

Super-Kは m2 ~ 10-3 eV2 2310 h

CDM と HDM の違いは

宇宙の構造形成に大きく影響する

(B) 天体的候補

•BBN を満足させるには Primordial Black Holeのみ

•Halo の成分だけなら通常の天体でも可能？

Massive Compact Halo Object (MACHO)

(4) MACHOThe MACHO Project: Microlensing Results from 5.7 Years of LMC Observations :ApJ.542(2000)281

What they have done•toward LMC: 5.7yr data•1.19107stars13~17events•variability of 34~230days

fit

ampl

ific

atio

n

What they have found•expected from usual stars:2~4events

MACHO exist•optical depth

1/2 compare to the previous result

74.03.0 102.1

•inconsistent with LMC/LMC-disk self lensing

•consistent with halos of Milky Way or LMC

•If they are halo events, MACHO is:

20% halo fraction for standard halo model

8~50% halo fraction with 95% CL

100% MACHO halo is ruled out with 95%CL

mass:0.15~0.9M

total 6~131010M within 50kpc

standard halo modelFraction of MACHO

mas

s of

MA

CH

O

What is MACHO?

Perhaps White Dwarf (WD)!

•New cooling model of WD Hansen ApJ.520(99)680

much bluer than we thought if there is H-atmosphere

H2 provide strong opacity in infrared forcing the radiation out in the blue

•We had been looking for wrong ones.

•In HDF, faint blue, fast moving object!

Ibata et al ApJ524 (1999)L95

Hansen

blue red

He-atmosphere1kpc

2kpcH-atmosphere

MACHO is at most 50% of halo fraction

MACHO=M is unlikely

If White Dwarf, the amount is constrained by gamma-ray from distant sources (z=0.034)

Freese, et al. astro-ph/0002058

WD<(1-3)10-3h-1

Particle Dark Matter is still necessary!

§4. Structure FormationInteraction between components

photon

electron dark matterbaryon

gravityThomson Scatt

gravitystars, galaxy

gas

dark halo of galaxylarge scale structure

CMB

Two important epochs

•matter-radiation equality epoch

zeq=60000(h/0.5)2, 1012s, 104K

before: radiation dominant

after: matter dominant

•recombination

zeq=1300, 1013s, 103K

before: highly ionized

after: neutral, transparent

Evolution

2) After Equality epoch Inside horizon:

dark matter: major component evolve by self-gravity

1) Before Equality epoch Inside sound horizon:

photon & baryon = tightly coupled acoustic oscillations

dark matter: minor component cannot evolve

DM

DM

ln(1/(1+z))

equality

recomb

Baryon

Jeans cross

ln

DM

DM

ln(1/(1+z))

equality

recomb

Baryon

Jeans cross

ln

3) After Recombination photon & baryon: decoupled photon: free stream to us

CMBbaryon: grow (catch up with dark matter)

Large Scale Structure

DM

DM

ln(1/(1+z))

equality

recomb

Baryon

Jeans cross

ln

DM

DM

ln(1/(1+z))

equality

recomb

Baryon

Jeans cross

ln

If dark matter has large kinetic energy:

small scale fluct are erased by random motion

Massive Neutrino: Hot Dark Matter

Dark Matter: equality epoch

CMB: recombination epoch

Specific Scale & Observational Quantities

•Matter Density Fluctuations

Horizon Scale at matter-radiation equality epoch

Power Spectrum P(k) k; wave number

Information

0h: horizon scale at matter-radiation equality epoch

measured in [h-1Mpc]

Initial Power Spectrum: very large scale

Nature of dark matter: cutoff on small scale

k[hMpc-1]

P(k

)CDM high 0h

CDM low 0h

HDM high 0h1k

kk ln3

LSS cluster galaxies

Horizon at equality

small scalelarge scale

Initial

power

Observations

(1) Matter Density Fluctuations

Galaxy Redshift Survey

Past:

CfA, Las Campanas Redshift Survey, QDOT, …on going and future:

2dF (100,000 galaxies out of 200,000),

Sloan Digital Sky Survey, 2MASS, DEEP,

PSCz,...

Shape of the power spectrum

0h=0.2-0.3 (Peacock & Dodds 1994)

if h=0.7 (HST), 00.3

Amplitude of the power spectrum

COBE normalization & Clusters

low neutrino mass: m<0.6eV (Fukugita, Liu, NS 2000)

low density (Eke et al 1996, Kitayama, Suto 1997)

Eke, Cole, Frenk 1996

2dF vs. APM

2dF (Peacock et al.)

Mh=0.200.03, B/M=0.150.07

if h=0.7 (HST), 00.3

2dF Galaxy Redshift Surevey

Peacock et al. astro-ph/0105500

Loop hole

bias: Do galaxies really trace the mass?

Direct measurement of underling gravitational field

Peculiar Velocity Field

Weak Gravitational Lensing

Weak gravitational lensing

Measuring cosmic shear field:

distortion of the galaxy images by lensing

Witteman et al.

Nature 405, 143 (00)

28

2.1

2.12

~

)(~

M

M kP

Bacon D., Refregier A., Ellis. R., 2000, MNRAS, 318, 625

Kaiser N., Wilson G., Luppino G.~A., 2000, ApJ astro-ph/0003338

Maoli R., et al., 2001, A\&A, 368, 766

Van Waerbeke L., et al., 2000, A\&A, 358, 30

Van Waerbeke L., et al., 2001a, A\&A in press

Wittman D.~N., et al., 2000, Nature, 405, 143

Pirzkal et al., 2001, A&A in press, (astro-ph/0102330)

References

Van Waerbeke L., et al., 2001a, A\&A in press, astro-ph/0101511

Canada-France-Hawaii Telscpoe,

6.5 sq. deg. Field, ~40hours data

• M=0.3, =0.7, 8=0.9 CDM is consistent

+0.04- 0.05• 8 M

0.6 = 0.43

M

M=0.3,

=0, 8=0.9

M=0.3,

=0.7, 8=0.9

M=1,

=0, 8=0.6

Low density adiabatic CDM:

0=0.3, =0.7, H0=70km/s/Mpcsucceed remarkably well•distant SNe•H0 from HST key project•CMB anisotropies•Cosmic Age•Large Scale Structure of the Universe

matter power spectrum P(k):

shape parameter =0h=0.2~0.3

amplitude at 8h-1Mpc:8

§5.Success of -CDM

•Is CDM real?

•What is CDM?

•Why and how does universe have ?

CDM is just a big trickCDM is just a big trick

or reality?or reality?

CDM is still the most favorite dark matter candidate

BUT

Some modification is needed

Problems of CDM model:

structure formation on < 1Mpc

CDM predicts

• an overly dense core in the centers of gal and clusters

• an overly large number of halos within Local Group

• triaxial halos

5-1 CDM crisis on small scales?

Moore et al. ApJ Lett. 1998

High Resolution Simulations of CDM

1/(r1.4(1+(r/rc)1.4) (Moore et al. ApJ.Lett 1998)

r-1.4 in the center

Rotation Curve of galaxies

1/(1+(r/rc)2) (de Blok & McGaugh MNRAS 1997)

const. in the center

in 0.5h-1Mpc

Klypin et al.

ApJ 522(99)82

Klypin et al.

ApJ 522(99)82

in 0.4h-1Mpc

Self-interacting cold dark matter (Spergel and Steinhardt PRL 84(2000)3760)

Consider

•self-interaction dark matter

•large scattering cross-section

•negligible annihilation or dissipation

•1kpc to 1Mpc mean free path

XX=8.110-25cm2 (mx/GeV)(Mpc/)

>1Mpc no effect

<1kpc too spherical cluster cores

Predictions:

(1)centers of halos are spherical

(2)dark matter halos have cores

(3)substructure in inner regions rapidly suppressed

1) innermost regions of DM halos in massive clusters

are elliptical (Miralda-Escude astro-ph/0002050)

• gravitational lensing observations

XX<3.210-26cm2 (mx/GeV)

>25Mpc: ruled out?

Problems?

2) produce too large and too round cores

(Yoshida et al. astro-ph/0006134)

• numerical Simulations

Smaller cross-section

Larger cross-section

round/large coretriaxial/small core

3) too small velocity dispersion of Elliptical Galaxies

(Gnedin & Ostriker astro-ph/0010436)

4) appropriate particle candidates?

Particles with a conserver global charge (hidden baryon number?) interacting through a hidden gauge group (hidden color?)

Warm Dark Matter (WDM)

keV mass particles ~ cutoff at Mpc scale

Mpc)keV1/()5.1/()15.0/(2.0 15.129.015.02 XXXC mghR

Colin et al. ApJ 542(2000)622

Bode, Ostriker, Turok, astro-ph/0010389

Problem: hard to form small objects

• reionization before z>5: mX > 1.2keV

• Ly-alpha Forest: mX > 750eVBarkana, Haiman, Ostriker astro-ph/0102304

Narayanan et al. astro-ph/0005095

5-2 Dark Energy

What is ?

Quintessence (Steinhardt et al.)

Motivation:

avoid fine tuning problem of •5th element:,baryon, dark matter, •Scalar Field works as an effective

Should be: w=p/<0 (=-1 for )

=(dQ/dt)2/2+V(Q) p=(dQ/dt)2/2-V(Q)

=>slow evolution of Q field

Naturalness requires• as if radiation before matter-radiation euality•attractor solution

Zlatev et al. PRL82(1888)896

= a-3(1+w)

Influence on Cosmology

works as “weak”

•effects on CMB anisotropies:

change the matter-radiation equality epoch

•Constraint from high z SNe

modify the acceleration/deceleration

We have hope to determine the equation of state

w by SNe (at z~1) and/or CMB (z~1000)