Issue |
A&A
Volume 468, Number 3, June IV 2007
Extended baselines for the IRAM Plateau de Bure interferometer: First results
|
|
---|---|---|
Page(s) | 877 - 883 | |
Section | Extragalactic astronomy | |
DOI | https://doi.org/10.1051/0004-6361:20066177 | |
Published online | 24 April 2007 |
High-redshift Ly
emitters with a large equivalent width
Properties of i
-dropout galaxies with
an NB921-band depression in the Subaru deep field
1
INAF - Osservatorio Astrofisico di Arcetri, Largo Enrico Fermi 5, 50125 Firenze, Italy e-mail: tohru@arcetri.astro.it
2
National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 151-8588, Japan
3
Astronomical Institute, Graduate School of Science, Tohoku University, Aramaki, Aoba, Sendai 980-8578, Japan
4
INAF – Osservatorio Astrofisico di Roma, via di Frascati 33, 00040 Monte Porzio Catone, Italy
5
Dipartimento di Astronomia e Scienza dello Spazio, Università di Firenze, Largo E. Fermi 2, 50125 Firenze, Italy
6
Subaru Telescope, National Astronomical Observatory of Japan, 650 North A'ohoku Place, Hilo, HI 96720, USA
7
Department of Astronomy, University of California at Los Angeles, PO Box 951547, Los Angeles, CA 90095-1547, USA
8
Institute of Astronomy, Graduate School of Science, University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015, Japan
9
Department of Astronomy, Graduate School of Science, Kyoto University, Kitashirakawa, Sakyo, Kyoto 606-8502, Japan
10
Department of Physics, Graduate School of Science and Engineering, Ehime University, 2-5 Bunkyo-cho, Matsuyama 790-8577, Japan
Received:
3
August
2006
Accepted:
12
January
2007
We report new follow-up spectroscopy of -dropout
galaxies with an NB921-band depression found in the Subaru
Deep Field. The NB921-depressed
-dropout selection
method is expected to select galaxies with large
equivalent-width Lyα emission over a wide redshift
range,
. Two of four observed targets
show a strong emission line with a clear asymmetric profile,
identified as Lyα emitters at z = 6.11 and 6.00.
Their rest-frame equivalent widths are 153
and
114
, which are lower limits on the intrinsic
equivalent widths.
Through our spectroscopic observations (including
previous ones) of NB921-depressed
-dropout galaxies,
we identified 5 galaxies in total with a rest-frame equivalent
width larger than 100
at
out of
8 photometric candidates, which suggests that the
NB921-depressed
-dropout selection method is
possibly an efficient way to search for Lyα emitters
with a large Lyα equivalent width, in a wider redshift
range than with usual narrow-band excess techniques.
By combining these findings with our previous observational
results, we infer that the fraction of broad-band selected
galaxies having a rest-frame equivalent width larger than
100
is significantly higher at
(the cosmic age of ~1 Gyr) than that at
(~2 Gyr), being consistent with the idea
that the typical stellar population of galaxies is
significantly younger at
than that at
.
The NB921-depressed
-dropout galaxies may be
interesting candidates for hosts of massive, zero-metallicity
Population III stars.
Key words: cosmology: early universe / galaxies: evolution / galaxies: formation / galaxies: individual: J132345.6+271701 / galaxies: individual: J132519.4+271829 / galaxies: starburst
© ESO, 2007
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