Gemini H-band imaging of the field of a z=10 candidate

Abstract

We present a deep H-band image of the field of a candidate z=10 galaxy magnified by the foreground (z=0.25) cluster A1835. The image was obtained with NIRI on Gemini North to better constrain the photometry and investigate the morphology of the source. The image is approximately one magnitude deeper and has better spatial resolution (seeing was 0.4-0.5 arcsec) than the existing H-band image obtained with ISAAC on the VLT by Pello' et al. 2004. The object is not detected in our new data. Given the published photometry (H(AB)=25.0), we would have expected it to have been detected at more than ~7 sigma in a 1.4 arcsec diameter aperture. We obtain a limit of H(AB)>26.0 (3 sigma) for the object. A major part of the evidence that this object is at z=10 was the presence of a strong continuum break between the J and H band, attributed to absorption of all continuum shortward of 1216 Ang in the rest-frame of the object. Our H-band non-detection substantially reduces the magnitude of any break and therefore weakens the case that this object is at z=10. Without a clear continuum break, the identification of an emission line at 1.33745um as Ly-alpha at z~10 is less likely. We show that the width and flux of this line are consistent with an alternative emission line such as [OIII]5007 from an intermediate redshift HII/dwarf galaxy.