SIMBAD references

2011MNRAS.412.2579N - Mon. Not. R. Astron. Soc., 412, 2579-2586 (2011/April-3)

Lyα emitters at z= 6.5 in the SSA22 field: an area more neutral or void at the end of the re-ionization epoch.


Abstract (from CDS):

We present results of a survey of Lyα emitters (LAEs) at z= 6.5 which is thought to be the final epoch of the cosmic re-ionization. In a ≈530 arcmin2 deep image of the SSA22 field taken through a narrow-band filter NB912 installed in the Subaru/Suprime-Cam, we have found only 14 LAE candidates with LLyα ≳ 3 {x} 1042 erg/s. Even applying the same colour selection criteria, the number density of the LAE candidates is a factor of 3 smaller than that found at the same redshift in the Subaru Deep Field (SDF). Assuming the number density in the SDF is a cosmic average, the probability to have a number density equal to or smaller than that found in the SSA22 field is only 7 per cent if we consider fluctuation by the large-scale structure (i.e. cosmic variance) and Poisson error. Therefore, the SSA22 field may be a rare void at z= 6.5. On the other hand, we have found that the number density of i'-drop galaxies with 25.5 < z' < 26.0 in the SSA22 field agrees well with that in the SDF. If we consider a scenario that a larger neutral fraction of intergalactic hydrogen, x_ H I_, in the SSA22 field obscures a part of Lyα emission, x_H I_ in the SSA22 field should be about two times larger than that in the SDF. This can be translated into x_ H I_< 0.9 at z= 6.5 in the SSA22 field. A much larger survey area than previous ones is required to overcome a large fluctuation reported here and to obtain a robust constraint on x_ H I_at the end of the re-ionization from LAEs.

This work is based on data collected at Subaru Telescope and obtained from the Subaru-Mitaka-Okayama-Kiso Archive System (SMOKA), which is operated by the Astronomy Data Center, National Astronomical Observatory of Japan.

Abstract Copyright: 2011 The Authors Monthly Notices of the Royal Astronomical Society2011 RAS

Journal keyword(s): galaxies: high-redshift - intergalactic medium - cosmology: observations

Nomenclature: Fig. 5, Tables 2-3: [NIH2011] SSA22-z6p5-NN (Nos 1-14).

Simbad objects: 20

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