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基盤研究(B)
すばるHSC観測と宇宙再電離
大規模シミュレーションによる電離度マップの描画
On the correction for the intergalactic
attenuation of the direct Lyman
continuum observation
Akio K. INOUE
(Osaka Sangyo University)
1
Lyman Continuum Leakage and Cosmic Reionization @ Stockholm
2014/8/15
基盤研究(B)
すばるHSC観測と宇宙再電離
大規模シミュレーションによる電離度マップの描画
Before the IGM issue…
 MD46 “LyC” substructure
 VLT/ISAAC 15 hours on-source exposure
 Neither [OIII] nor Hβ line
 <1e-17 cgs (3-sig)
2
Data reduction by K. Murakawa
Lyman Continuum Leakage and Cosmic Reionization @ Stockholm
2014/8/15
基盤研究(B)
すばるHSC観測と宇宙再電離
大規模シミュレーションによる電離度マップの描画
But, we have confirmed!
SSA22a-
Nakajima et al. in preparation
F336W/F814W=0.3
(0.8” aperture)
3
Lyman Continuum Leakage and Cosmic Reionization @ Stockholm
2014/8/15
基盤研究(B)
すばるHSC観測と宇宙再電離
大規模シミュレーションによる電離度マップの描画
Contents
 Basics
 Observed LyC flux to escape fraction
 Intergalactic LyC attenuation
 Examples of previous works
 Monte Carlo simulation of IG attenuation




Procedure
Absorber statistics update
Redshift dependence of the attenuation
Subaru/Suprime-Cam NB359 attenuation
 For a specific line-of-sight?
 Summary
4
Contents
Lyman Continuum Leakage and Cosmic Reionization @ Stockholm
2014/8/15
基盤研究(B)
すばるHSC観測と宇宙再電離
大規模シミュレーションによる電離度マップの描画
Observed LyC to escape fraction
E.g., Inoue et al. 2005, A&A, 435, 471
 Definition of “LyC escape fraction”:
 “Relative” escape fraction by Steidel et al. (2001):
Observable?
 IGM attenuation:
 LyC is affected by IGM but UV(~1500A) not, then,
Spectral model assumption
5
Direct observations
Lyman Continuum Leakage and Cosmic Reionization @ Stockholm
Not observable
Basics
2014/8/15
基盤研究(B)
すばるHSC観測と宇宙再電離
大規模シミュレーションによる電離度マップの描画
Intergalactic LyC attenuation
E.g., Inoue & Iwata 2008, MNRAS, 387, 1681
 IGM effective optical depth:
Single cloud optical depth
IGM cloud distribution function
 For a power law column density distribution:
𝑑𝜏eff /𝑑𝑑 𝑁u
(arbitrary unit)
Most of IGM 𝜏eff comes from
𝜏cl ~1 − 10 absorbers.
 For LyC attenuation,
rare Lyman limit systems
(log10 (𝑁HI /cm−2 ) > 17.2)
are the main contributor.
Stochastic attenuation
6
𝜏cl = 1
10
NHI slope
𝛽 = −1.5
Single IGM cloud optical depth
Lyman Continuum Leakage and Cosmic Reionization @ Stockholm
Basics
2014/8/15
基盤研究(B)
すばるHSC観測と宇宙再電離
大規模シミュレーションによる電離度マップの描画
Examples of previous works
 Steidel et al. (2001)
 A mean correction derived from a QSO composite spectrum
 Shapley et al. (2006); Nestor et al. (2011, 2013)
 A Monte Carlo simulation based on the Madau (1995) absorber
function (see also Bershady et al. 1999)
 Siana et al. (2007, 2010)
 A Monte Carlo simulation based on an updated absorber function
 Iwata et al. (2009)
 A Monte Carlo simulation based on the absorber function updated by
Inoue & Iwata (2008)
 Vanzella et al. (2010)
 A Monte Carlo simulation based on the absorber function updated by
Inoue et al. (2011)
 Mostardri et al. (2013)
 A Monte Carlo simulation based on the absorber function measured by
Rudie et al. (2013)
7
Basics
Lyman Continuum Leakage and Cosmic Reionization @ Stockholm
2014/8/15
基盤研究(B)
すばるHSC観測と宇宙再電離
大規模シミュレーションによる電離度マップの描画
Contents
 Basics
 Observed LyC flux to escape fraction
 Intergalactic LyC attenuation
 Examples of previous works
 Monte Carlo simulation of IG attenuation




Procedure
Absorber statistics update
Redshift dependence of the attenuation
Subaru/Suprime-Cam NB359 attenuation
 For a specific line-of-sight?
 Summary
8
Contents
Lyman Continuum Leakage and Cosmic Reionization @ Stockholm
2014/8/15
基盤研究(B)
すばるHSC観測と宇宙再電離
大規模シミュレーションによる電離度マップの描画
Procedure
E.g., Inoue & Iwata 2008, MNRAS, 387, 1681
ｚ, NHI, ｂ
ｚ, NHI, ｂ
ｚ, NHI, ｂ
 Randomly generate absorbers along a simulated line-of-
sight based on a distribution function assumed:
𝜕3𝑁
= 𝑓 𝑧 𝑔 𝑁HI ℎ(𝑏)
𝜕𝑧𝜕𝑁HI 𝜕𝑏
Heart of the model
 Calculate optical depth spectra toward supposed objects
along the line-of-sight
 Repeat the process for a large number of lines-of-sight.
 Caveat: No correlation among absorbers and objects
9
Monte Carlo simulation of IG attenuation
Lyman Continuum Leakage and Cosmic Reionization @ Stockholm
2014/8/15
基盤研究(B)
すばるHSC観測と宇宙再電離
大規模シミュレーションによる電離度マップの描画
Absorber statistics update (1)
Inoue et al. 2014, MNRAS, 442, 1805; Inoue & Iwata in preparation
 Column density distribution
z=6.5
z=4.5
z=2.5
z=0.5
z=6.5
z=4.5
z=2.5
z=0.5
z=6.5
z=4.5
z=2.5
z=0.5
10
Monte Carlo simulation of IG attenuation
Lyman Continuum Leakage and Cosmic Reionization @ Stockholm
2014/8/15
基盤研究(B)
すばるHSC観測と宇宙再電離
大規模シミュレーションによる電離度マップの描画
Absorber statistics update (2)
Inoue et al. 2014, MNRAS, 442, 1805; Inoue & Iwata in preparation
 Redshift distribution
+ This work ＊ Inoue & Iwata (2008)
x Madau (1995)
LAF
LLS
DLA
11
N_LLS(M95) > N_LLS(II08) > N_LLS(New) ≈ observations at z<3
N_LLS(II08) > N_LLS(M95) > N_LLS(New) ≈ observations at 3<z<4
Monte Carlo simulation of IG attenuation
Lyman Continuum Leakage and Cosmic Reionization @ Stockholm
2014/8/15
基盤研究(B)
すばるHSC観測と宇宙再電離
大規模シミュレーションによる電離度マップの描画
Absorber statistics update (3)
Inoue et al. 2014, MNRAS, 442, 1805; Inoue & Iwata in preparation
 Lyα transmission  E.g., Becker et al. (2013)
Median (solid line) and 68% range (shaded)
12
Monte Carlo simulation of IG attenuation
Lyman Continuum Leakage and Cosmic Reionization @ Stockholm
2014/8/15
基盤研究(B)
すばるHSC観測と宇宙再電離
大規模シミュレーションによる電離度マップの描画
Absorber statistics update (4)
Inoue et al. 2014, MNRAS, 442, 1805; Inoue & Iwata in preparation
 Lyman limit mean-free-path
100 LoSs composite: Median (solid line) and 68% range (shaded)
O’Meara+11
Fumagalli+13
Prochaska+09
Rudie+13
Worseck+14
Shorter MFP  Larger LyC attenuation
13
Monte Carlo simulation of IG attenuation
Lyman Continuum Leakage and Cosmic Reionization @ Stockholm
2014/8/15
基盤研究(B)
すばるHSC観測と宇宙再電離
大規模シミュレーションによる電離度マップの描画
Redshift dependence of the attenuation
Median (line) and 68% range (shaded)
Inoue & Iwata in preparation
 IGM LyC transmission
 Large fluctuation
 Asymmetric distribution
 New > II08 > M95 at 1<z<4
 Chance to have 20% LyC
transmission at z~5 in the
new model
14
Monte Carlo simulation of IG attenuation
Lyman Continuum Leakage and Cosmic Reionization @ Stockholm
2014/8/15
基盤研究(B)
すばるHSC観測と宇宙再電離
大規模シミュレーションによる電離度マップの描画
Subaru/S-Cam NB359 attenuation
Inoue & Iwata in preparation
NB359
z=3.1
16%
50%
84%
New
0.47
0.74
3.04
Madau
1995
0.95
x2 difference
1.59
3.80
Inoue &
Iwata ’08
0.59
1.13
4.61
Inoue et
al. 2011
0.41
0.62
2.57
[mag]
15
Monte Carlo simulation of IG attenuation
Lyman Continuum Leakage and Cosmic Reionization @ Stockholm
2014/8/15
基盤研究(B)
すばるHSC観測と宇宙再電離
大規模シミュレーションによる電離度マップの描画
Contents
 Basics
 Observed LyC flux to escape fraction
 Intergalactic LyC attenuation
 Examples of previous works
 Monte Carlo simulation of IG attenuation




Procedure
Absorber statistics update
Redshift dependence of the attenuation
Subaru/Suprime-Cam NB359 attenuation
 For a specific line-of-sight?
 Summary
16
Contents
Lyman Continuum Leakage and Cosmic Reionization @ Stockholm
2014/8/15
基盤研究(B)
すばるHSC観測と宇宙再電離
大規模シミュレーションによる電離度マップの描画
Lyα transmission fluctuation for SSA22
Inoue et al. in preparation
 Composite of LBGs behind the z=3.1 proto-cluster
 Enhanced Lyα absorption
in the proto-cluster 
Larger absorbers’ density
around galaxies?
Blue contour:
z=3.1 LAE
density
Green symbols:
z=3.1 LBGs
Red cross:
z=3.1 IGM
probed LoSs
(LBGs at 3.2<z<3.8)
17
For a specific line-of-sight?
Lyman Continuum Leakage and Cosmic Reionization @ Stockholm
2014/8/15
基盤研究(B)
すばるHSC観測と宇宙再電離
大規模シミュレーションによる電離度マップの描画
Effect of enhanced density of absorbers
Inoue & Iwata in preparation
 Fluctuation of Lyα transmission 
fluctuation of absorbers’ number
density
NB359
z=3.1
16%
50%
84%
General
LoS
0.47
0.74
3.04
SSA22
LoS
0.50
0.1 mag increase
0.83
4.19
[mag]
18
For a specific line-of-sight?
Lyman Continuum Leakage and Cosmic Reionization @ Stockholm
2014/8/15
基盤研究(B)
すばるHSC観測と宇宙再電離
大規模シミュレーションによる電離度マップの描画
Summary
 To derive LyC escape fraction (or emissivity) of galaxies from
direct observations, we have to correct the IGM attenuation
against LyC.
 The correction based on a Monte Carlo simulation requires to
assume an absorber distribution function.
 Some distribution functions had been assumed in literature and
the resultant median LyC attenuation varies from 0.6 mag to 1.6
mag at z~3.
 Madau (1995) model seems to give an overcorrection at z~3.
 Number density of absorbers may be enhanced around galaxies,
but its effect may be as small as 0.1 mag in the median LyC
attenuation.
 If we have a large enough number of spectra of objects further
than the redshift observed in LyC, the attenuation tailored for
the specific line-of-sight can be obtained.
19
Summary
Lyman Continuum Leakage and Cosmic Reionization @ Stockholm
2014/8/15
基盤研究(B)
すばるHSC観測と宇宙再電離
大規模シミュレーションによる電離度マップの描画
Available IGM transmission spectra
 10,000 lines-of-sight for objects at z=0.1 to 7.0 with dz
of 0.1
 New model
 New model special for SSA22
 Inoue et al. (2011) model
 Inoue & Iwata (2008) model
 Madau (1995) model
 Tell me, if you need.
20
Summary
Lyman Continuum Leakage and Cosmic Reionization @ Stockholm
2014/8/15