Cucchiara, A. and Kulkarni, S. R. (2011) A Photometric Redshift of z ~ 9.4 for GRB 090429B. Astrophysical Journal, 736 (1). Art. No. 7. ISSN 0004-637X http://resolver.caltech.edu/CaltechAUTHORS:20110801-133257199
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Gamma-ray bursts (GRBs) serve as powerful probes of the early universe, with their luminous afterglows revealing the locations and physical properties of star-forming galaxies at the highest redshifts, and potentially locating first-generation (Population III) stars. Since GRB afterglows have intrinsically very simple spectra, they allow robust redshifts from low signal-to-noise spectroscopy, or photometry. Here we present a photometric redshift of z ~ 9.4 for the Swift detected GRB 090429B based on deep observations with Gemini-North, the Very Large Telescope, and the GRB Optical and Near-infrared Detector. Assuming a Small Magellanic Cloud dust law (which has been found in a majority of GRB sight lines), the 90% likelihood range for the redshift is 9.06 < z < 9.52, although there is a low-probability tail toward somewhat lower redshifts. Adopting Milky Way or Large Magellanic Cloud dust laws leads to very similar conclusions, while a Maiolino law does allow somewhat lower redshift solutions, though in all cases the most likely redshift is found to be z > 7. The non-detection of the host galaxy to deep limits (Y(AB) ~ 28, which would correspond roughly to 0.001L* at z = 1) in our late-time optical and infrared observations with the Hubble Space Telescope strongly supports the extreme-redshift origin of GRB 090429B, since we would expect to have detected any low-z galaxy, even if it were highly dusty. Finally, the energetics of GRB 090429B are comparable to those of other GRBs and suggest that its progenitor is not greatly different from those of lower redshift bursts.
|Additional Information:||© 2011 American Astronomical Society. Received 2011 February 18; accepted 2011 April 18; published 2011 June 28. The Gemini data, acquired under the program ID GN-2009A-Q-26, are based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the Science and Technology Facilities Council (United Kingdom), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministério da Ciência e Tecnologia (Brazil), and Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina). Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the Space Telescope Institute. STScI is operated by the association of Universities for Research in Astronomy, Inc. under the NASA contract NAS 5-26555. Data presented in this paper is associated with programme GO-11189. Part of the funding for GROND (both hardware as well as personnel) was generously granted by the Leibniz-Prize to Prof. G. Hasinger (DFG grant HA 1850/28-1). T.K. acknowledges support by the DFG cluster of excellence “Origin and Structure of the Universe.” A.R. acknowledges funding from the Science and Technology Funding Council. The Dark Cosmology Centre is funded by the Danish National Research Foundation. F.O.E. acknowledges funding of his Ph.D. through the Deutscher Akademischer Austausch-Dienst (DAAD). We thank Paul Hewett for helpful discussions about absolute infrared flux calibration.|
|Subject Keywords:||early universe; galaxies: high-redshift; gamma-ray burst: individual (GRB 090429R); techniques: photometric|
|Classification Code:||PACS: 98.70.Rz, 95.85.Kr, 98.58.Ca, 98.38.Cp, 97.20.Wt|
|Official Citation:||A Photometric Redshift of z ~ 9.4 for GRB 090429B A. Cucchiara et al. 2011 ApJ 736 7|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Jason Perez|
|Deposited On:||01 Aug 2011 21:32|
|Last Modified:||26 Dec 2012 13:26|
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