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A possible signature of primordial stellar populations in z=3 Lyman alpha emitters. Akio K. INOUE (Osaka Sangyo University) - PowerPoint PPT Presentation
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A possible signature of primordial stellar populations in z=3 Lyman alpha emittersAkio 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)
First Stars IV at Kyoto 2012 1
ContentsFinding Lyman continuum emitting LAEs
with SubaruExtreme strength of Lyman continuum of the
LAEsA 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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Subaru Lyman continuum searchz=3—4 is the unique (translucent) window to observe
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).
Iwata, Inoue, et al. 2009, ApJ, 692, 1287
Hubble Ultra Deep Field (NASA)
time
Neutral universe
Big B
ang(ionized)
Recom
bination
Ionized universe
Reionization
redshift ~6 ~1000
Earth’s atmosphere IGM attenuation(Inter-Galactic Medium)
z=3-4
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Subaru Lyman continuum searchIwata, Inoue, et al. 2009, ApJ, 692, 1287
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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NB359 NB497V R i’
Lyman continuum emitting LAEs~10% LAEs are detected in NB359
(rest~900A)NB359(900A)
NB359(900A)
R(1500A)
R(1500A)
ACS 814(2000A)
ACS 814(2000A)
Iwata, Inoue, et al. 2009, ApJ, 692, 1287
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Some show offset of Ly-A and Ly-CVLT/VIMOS
AGN
3 arcsec
Inoue et al. 2011, MNRAS, 411, 2336
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Strong Lyman continuum Observed LAEs●: LAE with LyC (No LyA offset)○: LAE with LyC ( LyA offset)■: LBG with LyC
Pop. Synth. model(fesc=1)Constant SFR▽: Normal Pop I/II(Salpeter IMF, Z=1 /50,1 /5Zo)Instantaneous 1Myr△: Normal Pop I/II×: Top-heavy IMF*: Massive EMP◇: Massive Pop III
Stronger Ly-C
Inoue et al. 2011, MNRAS, 411, 2336
Very young (~1 Myr) Normal Pop I/II+ median IGM + dust
NB359 is affected by IGM
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fesc=1
Strong Lyman continuum Observed LAEs●: LAE with LyC (No LyA offset)○: LAE with LyC ( LyA offset)■: LBG with LyC
Pop. Synth. model(fesc=1)Constant SFR▽: Normal Pop I/II(Salpeter IMF, Z=1 /50,1 /5Zo)Instantaneous 1Myr△: Normal Pop I/II×: Top-heavy IMF*: Massive EMP◇: Massive Pop III
Stronger Ly-C
Inoue et al. 2011, MNRAS, 411, 2336
Massive Pop III + median IGM+ dust
NB359 is affected by IGM
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fesc=1
Escape of Nebular ContinuumNebular Lyman continuum may escape if
stellar Lyman continuum escapes from galaxies!Recombination process produces Lyman
continuum.Photon-bounded nebula
neutral
ionized
No escape both of stellar and nebular Lyman continua
Matter-bounded nebula
neutral
ionized
Both of stellar and nebular Lyman continua can escape
Inoue 2010, MNRAS, 401, 1325
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fesc=0 0<fesc<1
escaping stellar + nebularintrinsic stellarintrinsic nebular
Lyman limit ‘bump’<= Energy re-distribution by nebulae
(assumed to be independent of l)
NB359
V R i’
Inoue 2010, MNRAS, 401, 1325
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Normal (Salpeter IMF), young (1 Myr) Pop II (Z=0.0004)
Inoue et al. 2011, MNRAS, 411, 2336
The sequence is a function of fesc.
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Cumulative probability of the IGM attenuation
Massive (~100 Msun), young (1 Myr) Pop II (Z=0.0004)
Inoue et al. 2011, MNRAS, 411, 2336
The sequence is a function of fesc.
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Cumulative probability of the IGM attenuation
Massive (~100 Msun), young (1 Myr) EMP
Inoue et al. 2011, MNRAS, 411, 2336
The sequence is a function of fesc.
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Cumulative probability of the IGM attenuation
Massive (~100 Msun), young (1 Myr) Pop III
Inoue et al. 2011, MNRAS, 411, 2336
The sequence is a function of fesc.
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Cumulative probability of the IGM attenuation
LAEs emitting Lyman continuum3 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 offsetPossibly 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.
Inoue et al. 2011, MNRAS, 411, 2336
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Pop III + normal: Two components?Normal Pop II with dust
+ Pop III (Lyman ‘bump’)Blue: no dust for Pop IICyan: E(B-V) = 0.1Green: E(B-V) = 0.2Red: 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!
Inoue et al. 2011, MNRAS, 411, 2336
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ConclusionLyman 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)
R (1600A)
u (930A)
i (1900A) z (2200A)
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)
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SED of a “bluest” LAE
Lyman limit “bump”!?
NB497
NB359
u B V R i’ z’
c
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A possible scenarioInoue et al. 2011, MNRAS, 411, 2336
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A possible scenarioInoue et al. 2011, MNRAS, 411, 2336
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A possible scenarioInoue et al. 2011, MNRAS, 411, 2336
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