Akio K. INOUE (Osaka Sangyo University)
Kousai, K. (Tohoku U), Iwata, I. (NAOJ), Matsuda, Y.
(Caltech), Nakamura, E. (Tohoku U), Horie, M. (Tohoku U),
Hayashino, T. (Tohoku U), Tapken, C. (MPIA), Akiyama, M.
(Tohoku U), Noll, S. (U Innsbruck), Yamada, T. (Tohoku U),
Burgarella, D. (OAMP), Nakamura, Y. (Tohoku U)
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Contents
 Finding Lyman continuum emitting LAEs with Subaru
 Extreme strength of Lyman continuum of the LAEs
 A new SED model with the Lyman limit ‘bump’
 An interpretation of the LAEs’ nature:
 Galaxies with massive Pop III or EMP stellar population?
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Iwata, Inoue, et al. 2009, ApJ, 692, 1287
Subaru Lyman continuum search
 z=3—4 is the unique (translucent) window to observe
redshift
time
~6
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Neutral
universe
Big Bang
(ionized)
Recombination
Ionized
universe
Reionization
Lyman continuum from ground-based large telescopes.
 Subaru/Suprime-Cam + custom-made narrowband filter
which captures Lyman continuum (~900 A) of galaxies in a
proto-cluster at z=3.1 (SSA22 field).
Hubble Ultra Deep Field (NASA)
Earth’s atmosphere
IGM attenuation
z=3-4
(Inter-Galactic Medium)
~1000
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Iwata, Inoue, et al. 2009, ApJ, 692, 1287
Subaru Lyman continuum search
NB359
NB497
V
R
i’
We pre-selected LAEs at z=3.1 by NB497 and confirmed their
Ly-alpha by spectroscopy (i.e. all our sample LAEs have spec-z),
then we observe their Lyman continuum by NB359.
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Iwata, Inoue, et al. 2009, ApJ, 692, 1287
Lyman continuum emitting LAEs
 ~10% LAEs are detected in NB359 (rest~900A)
NB359
R
ACS 814
(900A) (1500A) (2000A)
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NB359
R
ACS 814
(900A) (1500A) (2000A)
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Inoue et al. 2011, MNRAS, 411, 2336
Some show offset of Ly-A and Ly-C
ＶＬＴ／
ＶＩＭＯＳ
３arcsec
ＡＧＮ
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Inoue et al. 2011, MNRAS, 411, 2336
Strong Lyman continuum
fesc=1
Very young (~1 Myr)
Normal Pop I/II
+ median IGM
+ dust
Observed LAEs
●：
LAE with LyC
(No LyA
offset)
○： LAE with LyC
（LyA offset）
■： LBG with LyC
Pop. Synth. model
(fesc=1)
NB359 is affected by IGM
Stronger Ly-C
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Constant SFR
▽： Normal Pop
I/II
（Ｓａｌｐｅｔｅｒ
ＩＭＦ，
Ｚ＝１/５０，１/５
Ｚｏ）
Instantaneous １Ｍ
7
ｙｒ
Inoue et al. 2011, MNRAS, 411, 2336
Strong Lyman continuum
fesc=1
Massive Pop III
+ median IGM
+ dust
Observed LAEs
●：
LAE with LyC
(No LyA
offset)
○： LAE with LyC
（LyA offset）
■： LBG with LyC
Pop. Synth. model
(fesc=1)
NB359 is affected by IGM
Stronger Ly-C
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Constant SFR
▽： Normal Pop
I/II
（Ｓａｌｐｅｔｅｒ
ＩＭＦ，
Ｚ＝１/５０，１/５
Ｚｏ）
Instantaneous １Ｍ
8
ｙｒ
Inoue 2010, MNRAS, 401, 1325
Escape of Nebular Continuum
 Nebular Lyman continuum may escape if stellar
Lyman continuum escapes from galaxies!
 Recombination process produces Lyman continuum.
Photon-bounded nebula
fesc=0
Matter-bounded nebula
0<fesc<1
neutral
neutral
ionized
ionized
No escape both of stellar and
nebular Lyman continua
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Both of stellar and nebular
Lyman continua can escape
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Inoue 2010, MNRAS, 401, 1325
NB359
escaping stellar + nebular
intrinsic stellar
intrinsic nebular
VR
i’
Lyman limit ‘bump’
<= Energy re-distribution
by nebulae
(assumed to be independent of l)
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Inoue et al. 2011, MNRAS, 411, 2336
Normal (Salpeter IMF), young (1 Myr) Pop II (Z=0.0004)
Cumulative probability
of the IGM attenuation
The sequence is
a function of fesc.
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Inoue et al. 2011, MNRAS, 411, 2336
Massive (~100 Msun), young (1 Myr) Pop II (Z=0.0004)
Cumulative probability
of the IGM attenuation
The sequence is
a function of fesc.
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Inoue et al. 2011, MNRAS, 411, 2336
Massive (~100 Msun), young (1 Myr) EMP
Cumulative probability
of the IGM attenuation
The sequence is
a function of fesc.
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Inoue et al. 2011, MNRAS, 411, 2336
Massive (~100 Msun), young (1 Myr) Pop III
Cumulative probability
of the IGM attenuation
The sequence is
a function of fesc.
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Inoue et al. 2011, MNRAS, 411, 2336
LAEs emitting Lyman continuum
 3 LAEs without Ly-A offset
 They are probably ‘real’ Lyman continuum emitters.
 Even if we adopt the Lyman ‘bump’ model, these objects still favor
massive (~100 Msun) and young (~1 Myr) Pop III, EMP, or Pop II
galaxies with fesc~0.5.
 For the Pop II case, very massive IMF is required at Z~1/50 Zsun
which is much higher than that expected for the IMF transition.
 5 LAEs with Ly-A offset
 Possibly the NB359 source is different from Ly-A emitting source:
we may have a few foreground contaminations.
 However, it is statistically difficult that all the 5 are foreground:
P<1%
 These objects require massive (~100 Msun) and young (~1 Myr) Pop
III galaxies along a transparent line-of-sight even with the Lyman
‘bump’ model of fesc~0.5.
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Inoue et al. 2011, MNRAS, 411, 2336
Pop III + normal:
Two components?
 Normal Pop II with dust
+ Pop III (Lyman ‘bump’)
 Blue: no dust for Pop II
 Cyan: E(B-V) = 0.1
 Green: E(B-V) = 0.2
 Red: E(B-V) = 0.3
 Pop III of 0.1-10% in the
stellar mass is enough.
 LAEs seem to have more
Pop III than LBGs.
 Late Pop III at z=3!
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Conclusion
 Lyman continuum emitting LAEs at z=3 possibly have a
significant amount of the ‘primordial’ stellar population.
 Stellar mass fraction is ~1% (0.1-10%).
 In future, we hope to obtain a more robust signature by
spectroscopy.
 [OIII]/H-beta ratio can be an indicator (Inoue 2011).
 Near-infrared spectroscopy with TMT?
 We will enlarge the sample with Subaru/Hyper-Suprime-
Cam (HSC) which has 10 times larger FOV than the current
S-Cam.
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NIR spectroscopy to constrain Z
 [OIII]/Hb < 0.1
 Z < 1/1000 Zsun
Inoue 2011, MNRAS, 415, 2920
Close-up of
a “bluest” LAE
NB359(880A)
u (930A)
NB497-BV (Ly a)
• Only one strong emission
line at 4986 A suggests that
this is an object at z=3.1!
• FWHM of the line in
medium-resolution
spectrum is 300 km/s.
• Spatially extended line
image (1.”3 against 1.”0 PSF)
R (1600A)
i (1900A)
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z (2200A)
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SED of a “bluest”
LAE
ＮＢ４９７
c
ＮＢ３５９
Lyman limit “bump”!?
ｕ
Ｂ
Ｖ
Ｒ
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ｉ’
ｚ’
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Inoue et al. 2011, MNRAS, 411, 2336
A possible scenario
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Inoue et al. 2011, MNRAS, 411, 2336
A possible scenario
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Inoue et al. 2011, MNRAS, 411, 2336
A possible scenario
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