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)

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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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