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A possible signature of primordial stellar populations in z=3 Lyman alpha emitters

A possible signature of primordial stellar populations in z=3 Lyman alpha emitters. Akio K. INOUE (Osaka Sangyo University)

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A possible signature of primordial stellar populations in z=3 Lyman alpha emitters

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  1. A possible signature of primordial stellar populations in z=3 Lyman alpha emitters 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) First Stars IV at Kyoto 2012

  2. 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? First Stars IV at Kyoto 2012

  3. Subaru Lyman continuum search Iwata, Inoue, et al. 2009, ApJ, 692, 1287 • z=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). Hubble Ultra Deep Field (NASA) Earth’s atmosphere IGM attenuation (Inter-Galactic Medium) z=3-4 Ionized universe Neutral universe Big Bang (ionized) Recombination Reionization ~6 ~1000 redshift First Stars IV at Kyoto 2012 time

  4. Subaru Lyman continuum search Iwata, Inoue, et al. 2009, ApJ, 692, 1287 NB497 NB359 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. First Stars IV at Kyoto 2012

  5. Lyman continuum emitting LAEs Iwata, Inoue, et al. 2009, ApJ, 692, 1287 • ~10% LAEs are detected in NB359 (rest~900A) NB359 (900A) R (1500A) ACS 814 (2000A) NB359 (900A) R (1500A) ACS 814 (2000A) First Stars IV at Kyoto 2012

  6. Some show offset of Ly-A and Ly-C Inoue et al. 2011, MNRAS, 411, 2336 ＶＬＴ／ ＶＩＭＯＳ ３arcsec ＡＧＮ First Stars IV at Kyoto 2012

  7. Strong Lyman continuum Inoue et al. 2011, MNRAS, 411, 2336 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 fesc=1 Very young (~1 Myr) Normal Pop I/II + median IGM + dust NB359 is affected by IGM Stronger Ly-C First Stars IV at Kyoto 2012

  8. Strong Lyman continuum Inoue et al. 2011, MNRAS, 411, 2336 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 fesc=1 Massive Pop III + median IGM + dust NB359 is affected by IGM Stronger Ly-C First Stars IV at Kyoto 2012

  9. Escape of Nebular Continuum Inoue 2010, MNRAS, 401, 1325 • Nebular Lyman continuum may escape if stellar Lyman continuum escapes from galaxies! • Recombination process produces Lyman continuum. Matter-bounded nebula Photon-bounded nebula fesc=0 0<fesc<1 neutral neutral ionized ionized Both of stellar and nebular Lyman continua can escape No escape both of stellar and nebular Lyman continua First Stars IV at Kyoto 2012

  10. Inoue 2010, MNRAS, 401, 1325 NB359 escaping stellar + nebular intrinsic stellar intrinsic nebular V R i’ Lyman limit ‘bump’ <= Energy re-distribution by nebulae (assumed to be independent of l) First Stars IV at Kyoto 2012

  11. 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. First Stars IV at Kyoto 2012

  12. 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. First Stars IV at Kyoto 2012

  13. 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. First Stars IV at Kyoto 2012

  14. 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. First Stars IV at Kyoto 2012

  15. LAEs emitting Lyman continuum Inoue et al. 2011, MNRAS, 411, 2336 • 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. First Stars IV at Kyoto 2012

  16. 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! First Stars IV at Kyoto 2012

  17. 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. First Stars IV at Kyoto 2012

  18. First Stars IV at Kyoto 2012

  19. NIR spectroscopy to constrain Z • [OIII]/Hb< 0.1  Z < 1/1000 Zsun Inoue 2011, MNRAS, 415, 2920

  20. Close-up of a “bluest” LAE • 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) NB359(880A) u (930A) NB497-BV (Ly a) R (1600A) z (2200A) i(1900A) First Stars IV at Kyoto 2012

  21. SED of a “bluest” LAE ＮＢ４９７ c ＮＢ３５９ Lyman limit “bump”!? ｕ Ｂ Ｖ ｚ’ ｉ’ Ｒ First Stars IV at Kyoto 2012

  22. A possible scenario Inoue et al. 2011, MNRAS, 411, 2336 First Stars IV at Kyoto 2012

  23. A possible scenario Inoue et al. 2011, MNRAS, 411, 2336 First Stars IV at Kyoto 2012

  24. A possible scenario Inoue et al. 2011, MNRAS, 411, 2336 First Stars IV at Kyoto 2012

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