Precision Array to Probe the Epoch of Reionization Chris Carilli JPL, May 2013
Landau Damping of Baryonic Structure Formation in the Post Reionization Epoch
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Transcript of Landau Damping of Baryonic Structure Formation in the Post Reionization Epoch
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Landau Damping of Baryonic Structure Formation in the
Post Reionization Epoch
Feng-Yin Chang
Arxiv:1006.5777
Leung Center for
Cosmology and Particle Astrophysics (LeCosPA) ,
National Taiwan University
COSMO/CosPA 2010 , Tokyo
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Reionization
6ionz
plasma neutral gas plasma
KTion4102~
( from WMAP7)2.15.10
from QSO spectrum Becker,et al (2001)
Larson, et al (2010)
Bolton, et al (2010)
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Previous Studies• Effects of reionization on intergalactic medium (IGM) an
d low-mass galaxies were studied by many researches.
• In 1986, Rees and Ikeuchi independently pointed out the increasing of gas temperature during reionization could suppress the formation of small galaxies with mass less then Jeans mass.
• Gnedin (2000) proposed the filtering scale as the characteristic scale for the baryonic fluctuation, instead of Jeans scale, for linear and nonlinear regimes.
• Chen and Lai (2007) first consider the plasma collective effects on the baryonic structure formation, but their calculation is incomplete.
P,Chen& KC La,i PRL(2007)
Gnedin, ApJ (2000)
Rees, MNRAS (1986) Ikeuchi AP&SS(2986)
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Why Plasma Effects?
GyrHckmD ~/][10~ 02
110~ 181730
DD nN 110~ 17 p
Three Plasma Criteria:
Plasma collective effects:
plasma wave, Landau damping, instabilities….
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Plasma Waves
i
eeii
M
kTkTV
eeBee Tke 222 3 thp kv
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Linear Fluid Equations
)(42
)(42
22
2
bkbdkdbksbkbk
bkbdkddkdk
ffGca
kH
ffGH
p
Bs m
Tkc
3
5
3/5
2
p
Bs
ie
m
Tkc
~3
5~
3/5,1
2
ionized gases plasma
JJ kk /~
13.1/~
For2,24.0 HeZY
mean molecular weight
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Landau Damping
be TT
F.Chen
4.0~r
i
0.4 of one oscillation period the ion acoustic wave would be Landau-damped to e-fold of its initial amplitude.
The nonlinear empirical formula
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Solution of Baryon Fluctuation
ionJionion a
a
k
k
,~, 10
TTb
1,0 db ffFor simplicity,
2
4/2
4/1
4/5
1
1)24/1,(
dk
bk AA
2ln)4/(
1
1),()24/1,(
iq
dk
bk be ri
damping
where
,124,241 22 qQoscillation part
ln
4cosln
4sin5
),( 4/5 qq
qbi
2
2
22
2
1 12
5,
12
5
Q
QA
Q
QA
:~Jk const.
Gc
ak
sJ 4~~
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a
Jf a
a
ak
da
ak 0
2/1
22
'1
)(
'31
)/exp( 22fkk
Results
)/exp( 22fkk
Ionized gas
ionized gas
plasma w LD
plasma w/o LD
For ,7ionz
Gnedin &Hui, MNRAS(1998)
The suppression of modes with intermediate and high k due to Landau damping gives rise to a correction of kf
F.Y.Chang, P.Chen, ArXiv:,1006.5777
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Modified Filtering Scale
2ln1.0
1
1),(ln
1~
~
iq
f
J bek
k
),~/exp(),(/ 22
fdkbk kk
]2,8.0[
F.Y.Chang, P.Chen, ArXiv:,1006.5777
.~~/
~constkk JF
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Jf kk /~
)~/exp( 22
fkk
ionized gas
plasma
Results
3
3
~//
~
~3
4~
FFFF
F
F
kkMM
ak
M
)(a
)(b The two characteristic wavenumbers for plasma and ionized gas deviate larger in high redshift.
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Landau Damping on Early Evolution
4/5
max)(
iondk
bk
a
ak
The small-scale baryon acoustic oscillations in early post-reionization epoch
can help distinguish the models
plasma
ionized gas
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Recent measurements
We are hereTegmark et. al, 2002
sunF
F
MM
hMpcOk10
1
10~
,)1(~
KT 410~
We seek for a cosmological survey for small-scale structure formation.
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Summary• The plasma collective effects on baryonic structu
re formation in the post-reionization is considered.
• Two major plasma influences: sound speed and Landau damping.
• The ion acoustic modes were rapidly smoothed out due to the Landau damping.
• The Landau damped spectrum should be characterized by a modified filtering scale.
• Measurement of small-scale baryonic oscillation is essential to learn the nature of the cosmic structure formation.