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Baryon Acoustic Baryon Acoustic Oscillations Oscillations Atsushi Taruya (RESCEU, Univ.Tokyo) 2009/01/14 すすすすすすすすすすすすすす @ すすす RESCEU=RESearch Center for the Early Univers

Baryon Acoustic Oscillations

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2009/01/14 すばるユーザーズミーティング @ 天文台. Baryon Acoustic Oscillations. Atsushi Taruya (RESCEU, Univ.Tokyo). RESCEU= RES earch C enter for the E arly U niverse. Contents. Baryon acoustic oscillation and cosmology. BAO measurement with WFMOS. Activity of Japan BAO theory group. - PowerPoint PPT Presentation

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Page 1: Baryon Acoustic Oscillations

Baryon Acoustic Baryon Acoustic OscillationsOscillations

Atsushi Taruya(RESCEU, Univ.Tokyo)

2009/01/14すばるユーザーズミーティング@ 天文台

RESCEU=RESearch Center for the Early Universe

Page 2: Baryon Acoustic Oscillations

Contents

Baryon acoustic oscillation and cosmology

BAO measurement with WFMOS

Activity of Japan BAO theory group

Page 3: Baryon Acoustic Oscillations

Baryon Acoustic Oscillation (BAO)

Acoustic oscillations of primeval baryon-photon fluid

imprinted on the clustering of large-scale structure

Detection & Observation of BAOs:

SDSS main, LRG samples

2dF GRS

Eisenstein et al. 2005; Cole et al.2005; Hutsui 2006; Percival et al. 2007; Okumura et al. 2008; Cabre et al. 2008; Gaztanaga et al. 2008

Typical

size

z

Page 4: Baryon Acoustic Oscillations

Observations of BAOsgalaxies102.5 5galaxies107.4 4

Eisenstein et al.(2005) Percival et al. (2007)

Page 5: Baryon Acoustic Oscillations

Physics of BAOs ~brief sketch~

BAO was imprinted around the time of decoupling of photons from matter

~380,000 ~380,000 year after the Big-Bangyear after the Big-Bang

Before decoupling,

CDM

baryon( electron )

photon

Gravitational growth

Thomson scattering

Before the time of decoupling, the Universe was in the plasma state, and photons and baryons (electron) were tightly coupled via Thomson scattering

Baryon-photons fluid

Acoustic mode

)})(4/3(1{3 photonbaryon

ccs

sound velocit

yCDM

baryon

Gravitational growth

photon

After decoupling,

After the decoupling, acoustic patterns of photon and baryon density fields were frozen, and baryon density field has evolved with dark matter under the influence of gravity

Page 6: Baryon Acoustic Oscillations

Characteristic Scale of BAOsSound horizon scale at the time of decoupling

Mpc023.013.0147)'(

)'(')(

08.02b

25.02mdec

dec

hh

zH

zcdzzr

z

ss

• Physics of BAOs is well-known, unambiguous(c.f. type Ia SNe )

:1089dez

• Insensitive to the presence of dark energy (Only weakly depends on matter and baryon density parameters)

• There’s no significant disturbances that erase acoustic patterns

BAO scale is a robust standard ruler

Page 7: Baryon Acoustic Oscillations

Measuring Expansion History

s

A

rzD )(

Redshift zAngular diameter distance

sr

In addition, Hubble parameter of distant objects, H(z), can be measured through Alcock & Paczynski effect.

cosmological distance of high-z objects can be measured

Using BAO scale as standard ruler,sr

sr

Nature of dark energydark energy

Constraints on expansion history

DA(z) and H(z) can be also used for tests of general relativity general relativity and Copernican Copernican principleprinciple

redshift

H(z)

DA(z)

Page 8: Baryon Acoustic Oscillations

Future BAO Measurement

Narrowing constraints on dark energy

A percent-level determination of H(z) & DA(z) :

%3 ww

%25/ dzdwdzdw

Minimal requirement

33survey Gpc5 hV

6gal 102N

c.f. SDSS LRG:

33survey Gpc7.0~ hV

2dF GRS:33

survey Gpc1.0~ hV

survey2

2

modesgalmodes 2

;)(

11

2

)(

)(V

kkN

kPnNkP

kP

Planned WFMOS survey (z~1 & 3) satisfies this requirement, andis complementary to other BAO experiments (BOSS,

HETDEX, …)

Page 9: Baryon Acoustic Oscillations

Toward Precision Measurement

accurate theoretical templates for P(k) and (r)

Precision measurement of BAOs needs

in order to determine the BAO scale

Systematic effects on BAOs:

Non-linear gravitational evolution

Redshift-space distortion

Galaxy biasing

small, but non-negligibleeffects at percent level

Development of theoretical modeling and feasibility study for precision measurement

Page 10: Baryon Acoustic Oscillations

Japan BAO Theory Group

Univ. Tokyo

IPMU

Nagoya Univ.

Hiroshima Univ.

T.Hiramatsu (ICRR), T.Nishimichi, S.Saito, Y.Suto, A.Taruya

I.Kayo, M.Takada, N.Yoshida

T.Matsubara, N.Sugiyama, R.Takahashi

H.Nomura, K.Yamamoto

People who are interested in BAO are very welcome !!

(friends ?)

NAOJT.Hamana, A.Nishizawa

Page 11: Baryon Acoustic Oscillations

Publications

Nishimichi et al. 2009, PASJ, in press (arXiv:0810.0813)Nishimichi et al. 2009, PASJ, in press (arXiv:0810.0813)

Saito, Takada & Taruya 2008, PRL 100, Saito, Takada & Taruya 2008, PRL 100, 191301191301

Taruya & Hiramatsu 2008, ApJ 674, 617Taruya & Hiramatsu 2008, ApJ 674, 617

Nishimichi et al. 2007, PASJ 59, 1049 Nishimichi et al. 2007, PASJ 59, 1049

Matsubara 2008, PRD 77, Matsubara 2008, PRD 77, 063530

Takahashi et al. 2009, in prep.Takahashi et al. 2009, in prep.

Matsubara 2008, PRD 78, Matsubara 2008, PRD 78, 083519

Taruya et al. 2009, in prep.Taruya et al. 2009, in prep.

Takahashi et al. 2008, MNRAS 389, 1675 Takahashi et al. 2008, MNRAS 389, 1675

Nomura, Yamamoto & Nishimichi 2008, JCAP 10, 031 Nomura, Yamamoto & Nishimichi 2008, JCAP 10, 031

Yamamoto et al. 2006, PRD 74, 063525Yamamoto et al. 2006, PRD 74, 063525Yamamoto et al. 2007, PRD 76, 023504Yamamoto et al. 2007, PRD 76, 023504

Page 12: Baryon Acoustic Oscillations

Modeling Non-linear Evolution

• Check of convergence regime of N-body simulations and analytic models

• Development of new analytic treatment based on perturbation theory

Accurate and reliable template for BAOs

• Reduction of numerical systematics in N-bosy simulations

(1% precision)

Error forecast including non-Gaussian error is also developed.

Page 13: Baryon Acoustic Oscillations

Modeling Non-linear Evolution

Real spaceReal space

P(k

)/P

smooth

(k) (r)

z=0.5

1

2

z=3

Page 14: Baryon Acoustic Oscillations

Modeling Non-linear Evolution

Redshift spaceRedshift space

P(k

)/P

smooth

(k) (r)

z=0.5

1

2

z=3

(monopole)

Page 15: Baryon Acoustic Oscillations

Feasibility

Nishimichi et al. (2009)

D/D

kmax [h/Mpc]

Linear (Idealistic)Non-linear

0.1

0.01

0.0010 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4

Distanceestimation error

Improved PT valid

Improved PT valid

Page 16: Baryon Acoustic Oscillations

SummaryMeasurement of BAOs with future redshift surveys opens a new window to probe cosmic expansion history

Acoustic signature of primeval baryon-photon fluidcan be used as cosmic standard ruler

Measurement of BAOs leads to Simultaneous determination

)()( zHzDA and

Mpc150)( 1dec

hzrs

of

Nature of dark energy (equation-of-state parameter)

Test of general relativity / cosmological principle

(~1% precision in WFMOS)

Japan BAO theory group seriously considers BAO experiment with WFMOS. Theoretical tools are now

developing.