J/ApJ/648/7 Lyα emitters at z=6.5 in Subaru Deep Field (Kashikawa+, 2006)
The end of the reionization epoch probed by Lyα emitters at z = 6.5 in the
Subaru Deep Field.
Kashikawa N., Shimasaku K., Malkan M.A., Doi M., Matsuda Y., Ouchi M.,
Taniguchi Y., Ly C., Nagao T., Iye M., Motohara K., Murayama T.,
Murozono K., Nariai K., Ohta K., Okamura S., Sasaki T., Shioya Y.,
Umemura M.
<Astrophys. J., 648, 7-22 (2006)>
=2006ApJ...648....7K 2006ApJ...648....7K
ADC_Keywords: Surveys ; Redshifts
Keywords: cosmology: observations - early universe - galaxies: formation -
galaxies: high-redshift
Abstract:
We report an extensive search for Lyα emitters (LAEs) at z=6.5
in the Subaru Deep Field. Subsequent spectroscopy with Subaru and Keck
identified eight more LAEs, giving a total of 17 spectroscopically
confirmed LAEs at z=6.5. Based on this spectroscopic sample of 17,
complemented by a photometric sample of 58 LAEs, we have derived a
more accurate Lyα luminosity function of LAEs at z=6.5, which
reveals an apparent deficit at the bright end of ∼0.75mag fainter L*,
compared with that observed at z=5.7. The difference in the LAE
luminosity functions between z=5.7 and 6.5 is significant at the
3σ level, which is reduced to 2σ when cosmic variance is
taken into account. This result may imply that the reionization of the
universe has not been completed at z=6.5. We found that the spatial
distribution of LAEs at z=6.5 was homogeneous over the field. We
discuss the implications of these results for the reionization of the
universe.
Description:
Our z6p5LAE photometric candidate sample in the SDF was presented in
Taniguchi et al. (Cat. J/PASJ/57/165), in which sample selection and
star formation rate density were discussed.
The z6p5LAE candidates were observed with the Keck II DEIMOS
spectrograph on UT 2004 April 23-24.
Three z6p5LAE candidates were also observed with the Subaru Faint
Object Camera and Spectrograph (FOCAS) spectrograph in the MOS mode on
UT 2004 April 24-27.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 67 8 Spectroscopic Properties of z=6.5 LAEs
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See also:
J/PASJ/57/881 : Imaging of high-redshift Lyman alpha emitters (Yamada+, 2005)
J/A+A/431/793 : Ly-alpha emitters around MRC 0316-257 (Venemans+, 2005)
J/PASJ/57/165 : Lyα emitters in the SUBARU Deep Field (Taniguchi+, 2005)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- [TAN2005] Sequential number
4- 6 A3 --- --- [SDF]
8- 23 A16 --- SDF SDF designation (JHHMMSS.s+DDMMSS)
25- 29 F5.3 --- z Redshift (1)
31- 35 F5.2 10-21W/m2 F(Lya) Observed line flux in Lyα (2)
37- 40 F4.2 10+35W L(Lya) Estimated Lyα luminosity (3)
42- 45 F4.2 solMass/yr SFR(Lya) Lyα Stellar Formation Rate (3)(4)
47- 50 F4.1 0.1nm FWHM FWHM in Angstroem (5)
52- 54 I3 km/s FWHM2 FWHM in km/s (5)
56- 60 F5.2 0.1nm Sw ? Weighted skewness (quantifies the
asymmetry of the emission lines)
62- 65 F4.2 0.1nm e_Sw rms uncertainty on Sw
67 A1 --- Obs [FD] Observed with FOCAS (F) or DEIMOS (D)
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Note (1): The redshift was derived from the wavelength of the flux peak in
an observed spectrum assuming the rest wavelength of Lyα to be
1215Å. These measurements could be overestimated in the case of
significant damping wings by IGM. Also, the observed peak position was
slightly shifted redward due to instrumental resolution. See Fig. 9.
Note (2): The observed line flux corresponds to the total amount.
Note (3): No dust absorption correction was applied.
Note (4): Estimated from the observed luminosities with the relation.
SFR(Lya)=9.1x10-43L(Lya)M☉/yr as in Taniguchi et al. (2005,
Cat. J/PASJ/57/165).
Note (5): Corrected for instrumental broadening.
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 04-Oct-2007