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DEEP2 Galaxy Redshift Survey: Redshift Identification of Single‐Line Emission Galaxies

Kirby, Evan N. and Guhathakurta, Puragra and Faber, S. M. and Koo, David C. and Weiner, Benjamin J. and Cooper, Michael C. (2007) DEEP2 Galaxy Redshift Survey: Redshift Identification of Single‐Line Emission Galaxies. Astrophysical Journal, 660 (1). pp. 62-71. ISSN 0004-637X. doi:10.1086/513464.

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We present two methods for determining spectroscopic redshifts of galaxies in the DEEP2 survey which display only one identifiable feature, an emission line, in the observed spectrum ("single-line galaxies"). First, we assume each single line is one of the four brightest lines accessible to DEEP2: Hα, [O III] λ5007, Hβ, or [O II] λ3727. Then, we supplement spectral information with BRI photometry. The first method, parameter-space proximity (PSP), calculates the distance of a single-line galaxy to galaxies of known redshift in (B - R), (R - I), R, λ_(observed) parameter space. The second method is an artificial neural network (ANN). Prior information, such as allowable line widths and ratios, rules out one or more of the four lines for some galaxies in both methods. Based on analyses of evaluation sets, both methods are nearly perfect at identifying blended [O II] doublets. Of the lines identified as Hα in the PSP and ANN methods, 91.4% and 94.2%, respectively, are accurate. Although the methods are not this accurate at discriminating between [O III] and Hβ, they can identify a single line as one of the two, and the ANN method in particular unambiguously identifies many [O III] lines. From a sample of 640 single-line spectra, the methods determine the identities of 401 (62.7%) and 472 (73.8%) single lines, respectively, at accuracies similar to those found in the evaluation sets.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Kirby, Evan N.0000-0001-6196-5162
Guhathakurta, Puragra0000-0001-8867-4234
Faber, S. M.0000-0003-4996-214X
Koo, David C.0000-0003-3385-6799
Cooper, Michael C.0000-0003-1371-6019
Additional Information:© 2007. The American Astronomical Society. Received 2006 December 28; accepted 2007 January 29. We thank the referee for a helpful report. We also thank J. A. Newman for providing statistics on repeat observations, and we thank C. M. Pierce for carefully reading a draft of this paper. We acknowledge National Science Foundation grants AST 05-07483 and AST 05-07428. E. N. K. is supported by a NSF Graduate Research Fellowship. Data herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.
Funding AgencyGrant Number
NSFAST 05-07483
NSFAST 05-07428
NSF Graduate Research FellowshipUNSPECIFIED
W. M. Keck FoundationUNSPECIFIED
Subject Keywords:galaxies: distances and redshifts; line: identification
Issue or Number:1
Record Number:CaltechAUTHORS:20190510-120908727
Persistent URL:
Official Citation:Evan N. Kirby et al 2007 ApJ 660 62
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:95411
Deposited By: George Porter
Deposited On:13 May 2019 19:32
Last Modified:16 Nov 2021 17:12

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