Identifying high-redshift gamma-ray bursts with RATIR

O. M. Littlejohns; Nathaniel Butler; A. Cucchiara; A. M. Watson; A. S. Kutyrev; W. H. Lee; M. G. Richer; C. R. Klein; O. D. Fox; J. X. Prochaska; J. S. Bloom; E. Troja; E. Ramirez-Ruiz; J. A. De Diego; L. Georgiev; J. González; C. G. Román-Zúñiga; N. Gehrels; H. Moseley

doi:10.1088/0004-6256/148/1/2

Identifying high-redshift gamma-ray bursts with RATIR

O. M. Littlejohns, Nathaniel Butler, A. Cucchiara, A. M. Watson, A. S. Kutyrev, W. H. Lee, M. G. Richer, C. R. Klein, O. D. Fox, J. X. Prochaska, J. S. Bloom, E. Troja, E. Ramirez-Ruiz, J. A. De Diego, L. Georgiev, J. González, C. G. Román-Zúñiga, N. Gehrels, H. Moseley

Earth and Space Exploration, School of (SESE)

Research output: Contribution to journal › Article › peer-review

8 Scopus citations

Abstract

We present a template-fitting algorithm for determining photometric redshifts, z_phot, of candidate high-redshift gamma-ray bursts (GRBs). Using afterglow photometry, obtained by the Reionization and Transients InfraRed (RATIR) camera, this algorithm accounts for the intrinsic GRB afterglow spectral energy distribution, host dust extinction, and the effect of neutral hydrogen (local and cosmological) along the line of sight. We present the results obtained by this algorithm and the RATIR photometry of GRB 130606A, finding a range of best-fit solutions, 5.6 < z_phot < 6.0, for models of several host dust extinction laws (none, the Milky Way, Large Magellanic Clouds, and Small Magellanic Clouds), consistent with spectroscopic measurements of the redshift of this GRB. Using simulated RATIR photometry, we find that our algorithm provides precise measures of z_phot in the ranges of 4 < z_phot ≲ 8 and 9 < z_phot < 10 and can robustly determine when z_phot > 4. Further testing highlights the required caution in cases of highly dust-extincted host galaxies. These tests also show that our algorithm does not erroneously find z _phot < 4 when z_sim > 4, thereby minimizing false negatives and allowing us to rapidly identify all potential high-redshift events.

Original language	English (US)
Article number	2
Journal	Astronomical Journal
Volume	148
Issue number	1
DOIs	https://doi.org/10.1088/0004-6256/148/1/2
State	Published - Jul 2014

Keywords

gamma-ray burst: general
gamma-ray burst: individual (GRB 130606A)
techniques: photometric Online-only material: color figures

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

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10.1088/0004-6256/148/1/2

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Littlejohns, O. M., Butler, N., Cucchiara, A., Watson, A. M., Kutyrev, A. S., Lee, W. H., Richer, M. G., Klein, C. R., Fox, O. D., Prochaska, J. X., Bloom, J. S., Troja, E., Ramirez-Ruiz, E., De Diego, J. A., Georgiev, L., González, J., Román-Zúñiga, C. G., Gehrels, N., & Moseley, H. (2014). Identifying high-redshift gamma-ray bursts with RATIR. Astronomical Journal, 148(1), Article 2. https://doi.org/10.1088/0004-6256/148/1/2

Littlejohns, OM, Butler, N, Cucchiara, A, Watson, AM, Kutyrev, AS, Lee, WH, Richer, MG, Klein, CR, Fox, OD, Prochaska, JX, Bloom, JS, Troja, E, Ramirez-Ruiz, E, De Diego, JA, Georgiev, L, González, J, Román-Zúñiga, CG, Gehrels, N & Moseley, H 2014, 'Identifying high-redshift gamma-ray bursts with RATIR', Astronomical Journal, vol. 148, no. 1, 2. https://doi.org/10.1088/0004-6256/148/1/2

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title = "Identifying high-redshift gamma-ray bursts with RATIR",

abstract = "We present a template-fitting algorithm for determining photometric redshifts, zphot, of candidate high-redshift gamma-ray bursts (GRBs). Using afterglow photometry, obtained by the Reionization and Transients InfraRed (RATIR) camera, this algorithm accounts for the intrinsic GRB afterglow spectral energy distribution, host dust extinction, and the effect of neutral hydrogen (local and cosmological) along the line of sight. We present the results obtained by this algorithm and the RATIR photometry of GRB 130606A, finding a range of best-fit solutions, 5.6 < zphot < 6.0, for models of several host dust extinction laws (none, the Milky Way, Large Magellanic Clouds, and Small Magellanic Clouds), consistent with spectroscopic measurements of the redshift of this GRB. Using simulated RATIR photometry, we find that our algorithm provides precise measures of zphot in the ranges of 4 < zphot ≲ 8 and 9 < zphot < 10 and can robustly determine when zphot > 4. Further testing highlights the required caution in cases of highly dust-extincted host galaxies. These tests also show that our algorithm does not erroneously find z phot < 4 when zsim > 4, thereby minimizing false negatives and allowing us to rapidly identify all potential high-redshift events.",

keywords = "gamma-ray burst: general, gamma-ray burst: individual (GRB 130606A), techniques: photometric Online-only material: color figures",

author = "Littlejohns, {O. M.} and Nathaniel Butler and A. Cucchiara and Watson, {A. M.} and Kutyrev, {A. S.} and Lee, {W. H.} and Richer, {M. G.} and Klein, {C. R.} and Fox, {O. D.} and Prochaska, {J. X.} and Bloom, {J. S.} and E. Troja and E. Ramirez-Ruiz and {De Diego}, {J. A.} and L. Georgiev and J. Gonz{\'a}lez and Rom{\'a}n-Z{\'u}{\~n}iga, {C. G.} and N. Gehrels and H. Moseley",

year = "2014",

month = jul,

doi = "10.1088/0004-6256/148/1/2",

language = "English (US)",

volume = "148",

journal = "Astronomical Journal",

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T1 - Identifying high-redshift gamma-ray bursts with RATIR

AU - Littlejohns, O. M.

AU - Butler, Nathaniel

AU - Cucchiara, A.

AU - Watson, A. M.

AU - Kutyrev, A. S.

AU - Lee, W. H.

AU - Richer, M. G.

AU - Klein, C. R.

AU - Fox, O. D.

AU - Prochaska, J. X.

AU - Bloom, J. S.

AU - Troja, E.

AU - Ramirez-Ruiz, E.

AU - De Diego, J. A.

AU - Georgiev, L.

AU - González, J.

AU - Román-Zúñiga, C. G.

AU - Gehrels, N.

AU - Moseley, H.

PY - 2014/7

Y1 - 2014/7

N2 - We present a template-fitting algorithm for determining photometric redshifts, zphot, of candidate high-redshift gamma-ray bursts (GRBs). Using afterglow photometry, obtained by the Reionization and Transients InfraRed (RATIR) camera, this algorithm accounts for the intrinsic GRB afterglow spectral energy distribution, host dust extinction, and the effect of neutral hydrogen (local and cosmological) along the line of sight. We present the results obtained by this algorithm and the RATIR photometry of GRB 130606A, finding a range of best-fit solutions, 5.6 < zphot < 6.0, for models of several host dust extinction laws (none, the Milky Way, Large Magellanic Clouds, and Small Magellanic Clouds), consistent with spectroscopic measurements of the redshift of this GRB. Using simulated RATIR photometry, we find that our algorithm provides precise measures of zphot in the ranges of 4 < zphot ≲ 8 and 9 < zphot < 10 and can robustly determine when zphot > 4. Further testing highlights the required caution in cases of highly dust-extincted host galaxies. These tests also show that our algorithm does not erroneously find z phot < 4 when zsim > 4, thereby minimizing false negatives and allowing us to rapidly identify all potential high-redshift events.

AB - We present a template-fitting algorithm for determining photometric redshifts, zphot, of candidate high-redshift gamma-ray bursts (GRBs). Using afterglow photometry, obtained by the Reionization and Transients InfraRed (RATIR) camera, this algorithm accounts for the intrinsic GRB afterglow spectral energy distribution, host dust extinction, and the effect of neutral hydrogen (local and cosmological) along the line of sight. We present the results obtained by this algorithm and the RATIR photometry of GRB 130606A, finding a range of best-fit solutions, 5.6 < zphot < 6.0, for models of several host dust extinction laws (none, the Milky Way, Large Magellanic Clouds, and Small Magellanic Clouds), consistent with spectroscopic measurements of the redshift of this GRB. Using simulated RATIR photometry, we find that our algorithm provides precise measures of zphot in the ranges of 4 < zphot ≲ 8 and 9 < zphot < 10 and can robustly determine when zphot > 4. Further testing highlights the required caution in cases of highly dust-extincted host galaxies. These tests also show that our algorithm does not erroneously find z phot < 4 when zsim > 4, thereby minimizing false negatives and allowing us to rapidly identify all potential high-redshift events.

KW - gamma-ray burst: general

KW - gamma-ray burst: individual (GRB 130606A)

KW - techniques: photometric Online-only material: color figures

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U2 - 10.1088/0004-6256/148/1/2

DO - 10.1088/0004-6256/148/1/2

M3 - Article

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SN - 0004-6256

VL - 148

JO - Astronomical Journal

JF - Astronomical Journal

IS - 1

M1 - 2

ER -

Identifying high-redshift gamma-ray bursts with RATIR

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Keywords

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