Baryon Acoustic Oscillations
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Transcript of 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
Contents
Baryon acoustic oscillation and cosmology
BAO measurement with WFMOS
Activity of Japan BAO theory group
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
Observations of BAOsgalaxies102.5 5galaxies107.4 4
Eisenstein et al.(2005) Percival et al. (2007)
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
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
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)
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, …)
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
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
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
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.
Modeling Non-linear Evolution
Real spaceReal space
P(k
)/P
smooth
(k) (r)
z=0.5
1
2
z=3
Modeling Non-linear Evolution
Redshift spaceRedshift space
P(k
)/P
smooth
(k) (r)
z=0.5
1
2
z=3
(monopole)
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
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.