Photometric redshifts in the IRAC shallow survey

M. Brodwin, M. J I Brown, M. L N Ashby, C. Bian, K. Brand, A. Dey, P. R. Eisenhardt, D. J. Eisenstein, A. H. Gonzalez, J. S. Huang, Buell Tomasson Jannuzi, C. S. Kochanek, E. McKenzie, S. S. Murray, M. A. Pahre, H. A. Smith, B. T. Soifer, S. A. Stanford, D. Stern, R. J. Elston

Research output: Contribution to journalArticle

116 Citations (Scopus)

Abstract

Accurate photometric redshifts are calculated for nearly 200,000 galaxies to a 4.5 μm flux limit of ∼13 μJy in the 8.5 deg2 Spitzer IRAC Shallow Survey. Using a hybrid photometric redshift algorithm incorporating both neural net and template-fitting techniques, calibrated with over 15,000 spectroscopic redshifts, a redshift accuracy of σ = 0.06(1 + z) is achieved for 95% of galaxies at 0 < z < 1.5. The accuracy is σ = 0.12(1 + z) for 95% of active galactic nuclei (AGNs) at 0 < z < 3. Redshift probability functions, central to several ongoing studies of the galaxy population, are computed for the full sample. We demonstrate that these functions accurately represent the true redshift probability density, allowing the calculation of valid confidence intervals for all objects. These probability functions have already been used to successfully identify a population of Spitzer-selected high-redshift (z > 1) galaxy clusters. We present one such spectroscopically confirmed cluster at 〈z〉 = 1.24, ISCS J1434.5+3427. Finally, we present a measurement of the 4.5 μm-selected galaxy redshift distribution.

Original languageEnglish (US)
Pages (from-to)791-803
Number of pages13
JournalAstrophysical Journal
Volume651
Issue number2 I
DOIs
StatePublished - Nov 10 2006
Externally publishedYes

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galaxies
neural nets
templates
distribution

Keywords

  • Galaxies: clusters: general
  • Galaxies: distances and redshifts
  • Galaxies: evolution
  • Galaxies: photometry
  • Methods: statistical

ASJC Scopus subject areas

  • Space and Planetary Science

Cite this

Brodwin, M., Brown, M. J. I., Ashby, M. L. N., Bian, C., Brand, K., Dey, A., ... Elston, R. J. (2006). Photometric redshifts in the IRAC shallow survey. Astrophysical Journal, 651(2 I), 791-803. https://doi.org/10.1086/507838

Photometric redshifts in the IRAC shallow survey. / Brodwin, M.; Brown, M. J I; Ashby, M. L N; Bian, C.; Brand, K.; Dey, A.; Eisenhardt, P. R.; Eisenstein, D. J.; Gonzalez, A. H.; Huang, J. S.; Jannuzi, Buell Tomasson; Kochanek, C. S.; McKenzie, E.; Murray, S. S.; Pahre, M. A.; Smith, H. A.; Soifer, B. T.; Stanford, S. A.; Stern, D.; Elston, R. J.

In: Astrophysical Journal, Vol. 651, No. 2 I, 10.11.2006, p. 791-803.

Research output: Contribution to journalArticle

Brodwin, M, Brown, MJI, Ashby, MLN, Bian, C, Brand, K, Dey, A, Eisenhardt, PR, Eisenstein, DJ, Gonzalez, AH, Huang, JS, Jannuzi, BT, Kochanek, CS, McKenzie, E, Murray, SS, Pahre, MA, Smith, HA, Soifer, BT, Stanford, SA, Stern, D & Elston, RJ 2006, 'Photometric redshifts in the IRAC shallow survey', Astrophysical Journal, vol. 651, no. 2 I, pp. 791-803. https://doi.org/10.1086/507838
Brodwin M, Brown MJI, Ashby MLN, Bian C, Brand K, Dey A et al. Photometric redshifts in the IRAC shallow survey. Astrophysical Journal. 2006 Nov 10;651(2 I):791-803. https://doi.org/10.1086/507838
Brodwin, M. ; Brown, M. J I ; Ashby, M. L N ; Bian, C. ; Brand, K. ; Dey, A. ; Eisenhardt, P. R. ; Eisenstein, D. J. ; Gonzalez, A. H. ; Huang, J. S. ; Jannuzi, Buell Tomasson ; Kochanek, C. S. ; McKenzie, E. ; Murray, S. S. ; Pahre, M. A. ; Smith, H. A. ; Soifer, B. T. ; Stanford, S. A. ; Stern, D. ; Elston, R. J. / Photometric redshifts in the IRAC shallow survey. In: Astrophysical Journal. 2006 ; Vol. 651, No. 2 I. pp. 791-803.
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AU - Brown, M. J I

AU - Ashby, M. L N

AU - Bian, C.

AU - Brand, K.

AU - Dey, A.

AU - Eisenhardt, P. R.

AU - Eisenstein, D. J.

AU - Gonzalez, A. H.

AU - Huang, J. S.

AU - Jannuzi, Buell Tomasson

AU - Kochanek, C. S.

AU - McKenzie, E.

AU - Murray, S. S.

AU - Pahre, M. A.

AU - Smith, H. A.

AU - Soifer, B. T.

AU - Stanford, S. A.

AU - Stern, D.

AU - Elston, R. J.

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N2 - Accurate photometric redshifts are calculated for nearly 200,000 galaxies to a 4.5 μm flux limit of ∼13 μJy in the 8.5 deg2 Spitzer IRAC Shallow Survey. Using a hybrid photometric redshift algorithm incorporating both neural net and template-fitting techniques, calibrated with over 15,000 spectroscopic redshifts, a redshift accuracy of σ = 0.06(1 + z) is achieved for 95% of galaxies at 0 < z < 1.5. The accuracy is σ = 0.12(1 + z) for 95% of active galactic nuclei (AGNs) at 0 < z < 3. Redshift probability functions, central to several ongoing studies of the galaxy population, are computed for the full sample. We demonstrate that these functions accurately represent the true redshift probability density, allowing the calculation of valid confidence intervals for all objects. These probability functions have already been used to successfully identify a population of Spitzer-selected high-redshift (z > 1) galaxy clusters. We present one such spectroscopically confirmed cluster at 〈z〉 = 1.24, ISCS J1434.5+3427. Finally, we present a measurement of the 4.5 μm-selected galaxy redshift distribution.

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KW - Galaxies: evolution

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