A narrow-band search for Ly alpha emitting galaxies at z = 8.8

Aims: The first star forming galaxies in the early universe should be copious Ly alpha emitters, and may play a significant role in ionizing the intergalactic medium (IGM). It has been proposed that the luminosity function of Lya emitting galaxies beyond z~6 may be used to constrain the neutral fraction of the IGM during this epoch. In this work we report on a search for Ly alpha emitters at redshift 8.8. Methods: We performed a narrow band imaging programme using ISAAC at the ESO VLT. Seven fields, covering a total area of 31sq. arcmin and for which optical and broad band infra-red images have been obtained in the GOODS survey, were imaged to a limiting flux (respectively luminosity) of ~ 1.3 x 10^{-17} ergs.s^{-1}.cm^{-2} (respectively ~ 1.3 x 10^{43} ergs.s^{-1} in a narrow band filter centered in a region of low OH sky emission at 1.19 micron. Candidate Lyman alpha emitters are objects that are detected in the ISAAC NB images and undetected in the visible broad band images. Results: No z=8.8 Ly alpha emitting galaxies were detected to a limit approaching recent estimates of the luminosity function at z ~ 6. Our results do suggest, however, that detections or substantial constraints could be achieved by this method in the near future with larger field instruments planned for various telescopes.

[1]  S. Okamura,et al.  The End of the Reionization Epoch Probed by Lyα Emitters at z = 6.5 in the Subaru Deep Field , 2006, astro-ph/0604149.

[2]  Mamoru Doi,et al.  Lyα Emitters at z = 5.7 in the Subaru Deep Field , 2006, astro-ph/0602614.

[3]  A. Hopkins,et al.  On the Normalization of the Cosmic Star Formation History , 2006, astro-ph/0601463.

[4]  T. Nagao,et al.  Narrowband Survey of the GOODS Fields: Search for Lyα Emitters at z = 5.7 , 2005, astro-ph/0510672.

[5]  C. Wolf,et al.  The Wide Field Imager Lyman-Alpha Search (WFILAS) for galaxies at redshift ~5.7: II. Survey design and sample analysis , 2006, astro-ph/0605019.

[6]  M. S. Burns,et al.  Spectroscopic confirmation of high-redshift supernovae with the ESO VLT , 2004, astro-ph/0410506.

[7]  E. al.,et al.  The SUBARU Deep Field Project: Lymanα Emitters at a Redshift of 6.6 , 2004, astro-ph/0407542.

[8]  Lausanne,et al.  A deep, narrow J-band search for protogalactic Lyα emission at redshifts z~ 9 , 2004, astro-ph/0412489.

[9]  Richard McMahon,et al.  DAzLE: the dark ages z (redshift) Lyman-α Explorer , 2004, SPIE Astronomical Telescopes + Instrumentation.

[10]  A. Cimatti,et al.  The manifold spectra and morphologies of EROs , 2003, astro-ph/0310742.

[11]  Chile,et al.  Discovery of a z = 6.17 galaxy from CFHT and VLT observations , 2003, astro-ph/0303646.

[12]  Norbert N. Hubin,et al.  SINFONI - Integral field spectroscopy at 50 milli-arcsecond resolution with the ESO VLT , 2003, SPIE Astronomical Telescopes + Instrumentation.

[13]  E. al.,et al.  The Discovery of Two Lyman α Emitters beyond Redshift 6 in the Subaru Deep Field , 2003 .

[14]  B. Krauskopf,et al.  Proc of SPIE , 2003 .

[15]  Arjun Dey,et al.  Spectroscopic Confirmation of Three Redshift z ≈ 5.7 Lyα Emitters from the Large-Area Lyman Alpha Survey , 2002, astro-ph/0209544.

[16]  J. Kneib,et al.  Erratum: “A Redshift z = 6.56 Galaxy behind the Cluster Abell 370” (ApJ, 568, L75 [2002]) , 2002 .

[17]  J. Kneib,et al.  A Redshift z = 6.56 Galaxy behind the Cluster Abell 370 , 2002, astro-ph/0203091.

[18]  V. Narayanan,et al.  Evolution of the Ionizing Background and the Epoch of Reionization from the Spectra of z ∼ 6 Quasars , 2001, astro-ph/0111184.

[19]  J. Rhoads,et al.  Large Equivalent Width Lyα line Emission at z=4.5: Young Galaxies in a Young Universe? , 2001, astro-ph/0111126.

[20]  R. McMahon,et al.  The Density of Lyα Emitters at Very High Redshift , 1998, astro-ph/9803011.

[21]  L. Cowie,et al.  High-z Lyα Emitters. I. A Blank-Field Search for Objects near Redshift z = 3.4 in and around the Hubble Deep Field and the Hawaii Deep Field SSA 22 , 1998, astro-ph/9801003.

[22]  Alexei V. Filippenko,et al.  Optical spectra of supernovae , 1997 .

[23]  E. Bertin,et al.  SExtractor: Software for source extraction , 1996 .

[24]  M. El-Aasser,et al.  Synthesis and characterization of core/shell ionomeric latexes. II. Surface analysis by X-ray photoelectron spectroscopy , 1995 .