The low-extinction afterglow in the solar-metallicity host galaxy of γ -ray burst 110918A

J. Elliott, T. Krühler, J. Greiner, S. Savaglio, F. Olivares, E. A. Rau, A. De Ugarte Postigo, R. Sánchez-Ramírez, K. Wiersema, P. Schady, D. A. Kann, R. Filgas, M. Nardini, E. Berger, D. Fox, J. Gorosabel, S. Klose, A. Levan, A. Nicuesa Guelbenzu, A. RossiS. Schmidl, V. Sudilovsky, N. R. Tanvir, C. C. Thöne

Research output: Contribution to journalArticle

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Abstract

Galaxies selected through long γ-ray bursts (GRBs) could be of fundamental importance when mapping the star formation history out to the highest redshifts. Before using them as efficient tools in the early Universe, however, the environmental factors that govern the formation of GRBs need to be understood. Metallicity is theoretically thought to be a fundamental driver in GRB explosions and energetics, but it is still, even after more than a decade of extensive studies, not fully understood. This is largely related to two phenomena: a dust-extinction bias, which prevented high-mass and thus likely high-metallicity GRB hosts from being detected in the first place, and a lack of efficient instrumentation, which limited spectroscopic studies, including metallicity measurements, to the low-redshift end of the GRB host population. The subject of this work is the very energetic GRB 110918A (E γ,iso = 1.9 × 1054 erg), for which we measure a redshift of z = 0.984. GRB 110918A gave rise to a luminous afterglow with an intrinsic spectral slope of β = 0.70, which probed a sight-line with little extinction (AGRBV = 0.16 magAVGRB=0.16 mag) and soft X-ray absorption (NH,X = (1.6 ± 0.5) × 1021 cm-2) typical of the established distributions of afterglow properties. However, photometric and spectroscopic follow-up observations of the galaxy hosting GRB 110918A, including optical/near-infrared photometry with the Gamma-Ray burst Optical Near-infrared Detector and spectroscopy with the Very Large Telescope/X-shooter, reveal an all but average GRB host in comparison to the z ∼1 galaxies selected through similar afterglows to date. It has a large spatial extent with a half-light radius of R1/2 ∼10R1210 kpc, the highest stellar mass for z < 1.9 (log (M -/M⊙) = 10.68 ± 0.16), and an Hα-based star formation rate of SFR = 41 +28-16SFRHα=41-16+28 M ⊙ yr-1. We measure a gas-phase extinction of AgasV ∼1.8 magAVgas1.8 mag through the Balmer decrement and one of the largest host-integrated metallicities ever of around solar using the well-constrained ratios of [N ii]/Hα and [N ii]/[O ii] (12 + log (O/H) = 8.93 ± 0.13 and 8.85+0.14 -0.188.85-0.18+0.14, respectively). This presents one of the very few robust metallicity measurements of GRB hosts at z ∼1, and establishes thatGRB hosts at z ∼1 can also be very metal rich. It conclusively rules out a metallicity cut-off in GRB host galaxies and argues against an anti-correlation between metallicity and energy release in GRBs.

Original languageEnglish (US)
Article numberA23
JournalAstronomy and Astrophysics
Volume556
DOIs
StatePublished - Jul 31 2013

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afterglows
metallicity
bursts
rays
extinction
galaxies
near infrared
energetics
infrared photometry
visual perception
erg
infrared detectors
instrumentation
star formation rate
stellar mass
explosion
gamma ray bursts
environmental factor
explosions
star formation

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Elliott, J., Krühler, T., Greiner, J., Savaglio, S., Olivares, F., Rau, E. A., ... Thöne, C. C. (2013). The low-extinction afterglow in the solar-metallicity host galaxy of γ -ray burst 110918A. Astronomy and Astrophysics, 556, [A23]. https://doi.org/10.1051/0004-6361/201220968
Elliott, J. ; Krühler, T. ; Greiner, J. ; Savaglio, S. ; Olivares, F. ; Rau, E. A. ; De Ugarte Postigo, A. ; Sánchez-Ramírez, R. ; Wiersema, K. ; Schady, P. ; Kann, D. A. ; Filgas, R. ; Nardini, M. ; Berger, E. ; Fox, D. ; Gorosabel, J. ; Klose, S. ; Levan, A. ; Nicuesa Guelbenzu, A. ; Rossi, A. ; Schmidl, S. ; Sudilovsky, V. ; Tanvir, N. R. ; Thöne, C. C. / The low-extinction afterglow in the solar-metallicity host galaxy of γ -ray burst 110918A. In: Astronomy and Astrophysics. 2013 ; Vol. 556.
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abstract = "Galaxies selected through long γ-ray bursts (GRBs) could be of fundamental importance when mapping the star formation history out to the highest redshifts. Before using them as efficient tools in the early Universe, however, the environmental factors that govern the formation of GRBs need to be understood. Metallicity is theoretically thought to be a fundamental driver in GRB explosions and energetics, but it is still, even after more than a decade of extensive studies, not fully understood. This is largely related to two phenomena: a dust-extinction bias, which prevented high-mass and thus likely high-metallicity GRB hosts from being detected in the first place, and a lack of efficient instrumentation, which limited spectroscopic studies, including metallicity measurements, to the low-redshift end of the GRB host population. The subject of this work is the very energetic GRB 110918A (E γ,iso = 1.9 × 1054 erg), for which we measure a redshift of z = 0.984. GRB 110918A gave rise to a luminous afterglow with an intrinsic spectral slope of β = 0.70, which probed a sight-line with little extinction (AGRBV = 0.16 magAVGRB=0.16 mag) and soft X-ray absorption (NH,X = (1.6 ± 0.5) × 1021 cm-2) typical of the established distributions of afterglow properties. However, photometric and spectroscopic follow-up observations of the galaxy hosting GRB 110918A, including optical/near-infrared photometry with the Gamma-Ray burst Optical Near-infrared Detector and spectroscopy with the Very Large Telescope/X-shooter, reveal an all but average GRB host in comparison to the z ∼1 galaxies selected through similar afterglows to date. It has a large spatial extent with a half-light radius of R1/2 ∼10R1210 kpc, the highest stellar mass for z < 1.9 (log (M -/M{\^a}Š™) = 10.68 ± 0.16), and an Hα-based star formation rate of SFRHα = 41 +28-16SFRHα=41-16+28 M {\^a}Š™ yr-1. We measure a gas-phase extinction of AgasV ∼1.8 magAVgas1.8 mag through the Balmer decrement and one of the largest host-integrated metallicities ever of around solar using the well-constrained ratios of [N ii]/Hα and [N ii]/[O ii] (12 + log (O/H) = 8.93 ± 0.13 and 8.85+0.14 -0.188.85-0.18+0.14, respectively). This presents one of the very few robust metallicity measurements of GRB hosts at z ∼1, and establishes thatGRB hosts at z ∼1 can also be very metal rich. It conclusively rules out a metallicity cut-off in GRB host galaxies and argues against an anti-correlation between metallicity and energy release in GRBs.",
author = "J. Elliott and T. Kr{\"u}hler and J. Greiner and S. Savaglio and F. Olivares and Rau, {E. A.} and {De Ugarte Postigo}, A. and R. S{\'a}nchez-Ram{\'i}rez and K. Wiersema and P. Schady and Kann, {D. A.} and R. Filgas and M. Nardini and E. Berger and D. Fox and J. Gorosabel and S. Klose and A. Levan and {Nicuesa Guelbenzu}, A. and A. Rossi and S. Schmidl and V. Sudilovsky and Tanvir, {N. R.} and Th{\"o}ne, {C. C.}",
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Elliott, J, Krühler, T, Greiner, J, Savaglio, S, Olivares, F, Rau, EA, De Ugarte Postigo, A, Sánchez-Ramírez, R, Wiersema, K, Schady, P, Kann, DA, Filgas, R, Nardini, M, Berger, E, Fox, D, Gorosabel, J, Klose, S, Levan, A, Nicuesa Guelbenzu, A, Rossi, A, Schmidl, S, Sudilovsky, V, Tanvir, NR & Thöne, CC 2013, 'The low-extinction afterglow in the solar-metallicity host galaxy of γ -ray burst 110918A', Astronomy and Astrophysics, vol. 556, A23. https://doi.org/10.1051/0004-6361/201220968

The low-extinction afterglow in the solar-metallicity host galaxy of γ -ray burst 110918A. / Elliott, J.; Krühler, T.; Greiner, J.; Savaglio, S.; Olivares, F.; Rau, E. A.; De Ugarte Postigo, A.; Sánchez-Ramírez, R.; Wiersema, K.; Schady, P.; Kann, D. A.; Filgas, R.; Nardini, M.; Berger, E.; Fox, D.; Gorosabel, J.; Klose, S.; Levan, A.; Nicuesa Guelbenzu, A.; Rossi, A.; Schmidl, S.; Sudilovsky, V.; Tanvir, N. R.; Thöne, C. C.

In: Astronomy and Astrophysics, Vol. 556, A23, 31.07.2013.

Research output: Contribution to journalArticle

TY - JOUR

T1 - The low-extinction afterglow in the solar-metallicity host galaxy of γ -ray burst 110918A

AU - Elliott, J.

AU - Krühler, T.

AU - Greiner, J.

AU - Savaglio, S.

AU - Olivares, F.

AU - Rau, E. A.

AU - De Ugarte Postigo, A.

AU - Sánchez-Ramírez, R.

AU - Wiersema, K.

AU - Schady, P.

AU - Kann, D. A.

AU - Filgas, R.

AU - Nardini, M.

AU - Berger, E.

AU - Fox, D.

AU - Gorosabel, J.

AU - Klose, S.

AU - Levan, A.

AU - Nicuesa Guelbenzu, A.

AU - Rossi, A.

AU - Schmidl, S.

AU - Sudilovsky, V.

AU - Tanvir, N. R.

AU - Thöne, C. C.

PY - 2013/7/31

Y1 - 2013/7/31

N2 - Galaxies selected through long γ-ray bursts (GRBs) could be of fundamental importance when mapping the star formation history out to the highest redshifts. Before using them as efficient tools in the early Universe, however, the environmental factors that govern the formation of GRBs need to be understood. Metallicity is theoretically thought to be a fundamental driver in GRB explosions and energetics, but it is still, even after more than a decade of extensive studies, not fully understood. This is largely related to two phenomena: a dust-extinction bias, which prevented high-mass and thus likely high-metallicity GRB hosts from being detected in the first place, and a lack of efficient instrumentation, which limited spectroscopic studies, including metallicity measurements, to the low-redshift end of the GRB host population. The subject of this work is the very energetic GRB 110918A (E γ,iso = 1.9 × 1054 erg), for which we measure a redshift of z = 0.984. GRB 110918A gave rise to a luminous afterglow with an intrinsic spectral slope of β = 0.70, which probed a sight-line with little extinction (AGRBV = 0.16 magAVGRB=0.16 mag) and soft X-ray absorption (NH,X = (1.6 ± 0.5) × 1021 cm-2) typical of the established distributions of afterglow properties. However, photometric and spectroscopic follow-up observations of the galaxy hosting GRB 110918A, including optical/near-infrared photometry with the Gamma-Ray burst Optical Near-infrared Detector and spectroscopy with the Very Large Telescope/X-shooter, reveal an all but average GRB host in comparison to the z ∼1 galaxies selected through similar afterglows to date. It has a large spatial extent with a half-light radius of R1/2 ∼10R1210 kpc, the highest stellar mass for z < 1.9 (log (M -/M⊙) = 10.68 ± 0.16), and an Hα-based star formation rate of SFRHα = 41 +28-16SFRHα=41-16+28 M ⊙ yr-1. We measure a gas-phase extinction of AgasV ∼1.8 magAVgas1.8 mag through the Balmer decrement and one of the largest host-integrated metallicities ever of around solar using the well-constrained ratios of [N ii]/Hα and [N ii]/[O ii] (12 + log (O/H) = 8.93 ± 0.13 and 8.85+0.14 -0.188.85-0.18+0.14, respectively). This presents one of the very few robust metallicity measurements of GRB hosts at z ∼1, and establishes thatGRB hosts at z ∼1 can also be very metal rich. It conclusively rules out a metallicity cut-off in GRB host galaxies and argues against an anti-correlation between metallicity and energy release in GRBs.

AB - Galaxies selected through long γ-ray bursts (GRBs) could be of fundamental importance when mapping the star formation history out to the highest redshifts. Before using them as efficient tools in the early Universe, however, the environmental factors that govern the formation of GRBs need to be understood. Metallicity is theoretically thought to be a fundamental driver in GRB explosions and energetics, but it is still, even after more than a decade of extensive studies, not fully understood. This is largely related to two phenomena: a dust-extinction bias, which prevented high-mass and thus likely high-metallicity GRB hosts from being detected in the first place, and a lack of efficient instrumentation, which limited spectroscopic studies, including metallicity measurements, to the low-redshift end of the GRB host population. The subject of this work is the very energetic GRB 110918A (E γ,iso = 1.9 × 1054 erg), for which we measure a redshift of z = 0.984. GRB 110918A gave rise to a luminous afterglow with an intrinsic spectral slope of β = 0.70, which probed a sight-line with little extinction (AGRBV = 0.16 magAVGRB=0.16 mag) and soft X-ray absorption (NH,X = (1.6 ± 0.5) × 1021 cm-2) typical of the established distributions of afterglow properties. However, photometric and spectroscopic follow-up observations of the galaxy hosting GRB 110918A, including optical/near-infrared photometry with the Gamma-Ray burst Optical Near-infrared Detector and spectroscopy with the Very Large Telescope/X-shooter, reveal an all but average GRB host in comparison to the z ∼1 galaxies selected through similar afterglows to date. It has a large spatial extent with a half-light radius of R1/2 ∼10R1210 kpc, the highest stellar mass for z < 1.9 (log (M -/M⊙) = 10.68 ± 0.16), and an Hα-based star formation rate of SFRHα = 41 +28-16SFRHα=41-16+28 M ⊙ yr-1. We measure a gas-phase extinction of AgasV ∼1.8 magAVgas1.8 mag through the Balmer decrement and one of the largest host-integrated metallicities ever of around solar using the well-constrained ratios of [N ii]/Hα and [N ii]/[O ii] (12 + log (O/H) = 8.93 ± 0.13 and 8.85+0.14 -0.188.85-0.18+0.14, respectively). This presents one of the very few robust metallicity measurements of GRB hosts at z ∼1, and establishes thatGRB hosts at z ∼1 can also be very metal rich. It conclusively rules out a metallicity cut-off in GRB host galaxies and argues against an anti-correlation between metallicity and energy release in GRBs.

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