Microphysics and dynamics of the gamma-ray burst 121024A

K. Varela, H. van Eerten, J. Greiner, P. Schady, J. Elliott, V. Sudilovsky, T. Krühler, A. J. van der Horst, J. Bolmer, F. Knust, C. Agurto, F. Azagra, A. Belloche, F. Bertoldi, C. De Breuck, C. Delvaux, R. Filgas, J. F. Graham, D. A. Kann, S. Klose & 11 others K. M. Menten, A. Nicuesa Guelbenzu, A. Rau, A. Rossi, S. Schmidl, F. Schuller, T. Schweyer, M. Tanga, A. Weiss, P. Wiseman, F. Wyrowski

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Abstract

Aims. The aim of the study is to constrain the physics of gamma-ray bursts (GRBs) by analysing the multi-wavelength afterglow data set of GRB 121024A that covers the full range from radio to X-rays. Methods. Using multi-epoch broad-band observations of the GRB 121024A afterglow, we measured the three characteristic break frequencies of the synchrotron spectrum. We used six epochs of combined XRT and GROND data to constrain the temporal slopes, the dust extinction, the X-ray absorption, and the spectral slope with high accuracy. Two more epochs of combined data from XRT, GROND, APEX, CARMA, and EVLA were used to set constraints on the break frequencies and therefore on the micro-physical and dynamical parameters. Results. The XRT and GROND light curves show a simultaneous and achromatic break at around 49 ks. As a result, the crossing of the synchrotron cooling break is no suitable explanation for the break in the light curve. The multi-wavelength data allow us to test two plausible scenarios explaining the break: a jet break, and the end of energy injection. The jet-break scenario requires a hard electron spectrum, a very low cooling break frequency, and a non-spreading jet. The energy injection avoids these problems, but requires ϵe > 1 (k = 2), spherical outflow, and ϵB < 10-9. Conclusions. In light of the extreme microphysical parameters required by the energy-injection model, we favour a jet-break scenario where νm < νsa to explain the observations. This scenario gives physically meaningful microphysical parameters, and it also naturally explains the reported detection of linear and circular polarisation.
Original languageEnglish
Article numberA37
Pages (from-to)A37
JournalAstronomy & Astrophysics
Volume589
Early online date11 Apr 2016
DOIs
Publication statusPublished - 1 May 2016

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gamma ray bursts
time measurement
injection
afterglows
light curve
synchrotrons
slopes
cooling
wavelength
energy
circular polarization
linear polarization
wavelengths
extinction
x rays
outflow
physics
polarization
dust
radio

Keywords

  • X-rays: bursts, gamma-ray burst: general, gamma-ray burst: individual: GRB 121024A, methods: observational, radiation mechanisms: non-thermal, stars: jets

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Microphysics and dynamics of the gamma-ray burst 121024A. / Varela, K.; van Eerten, H.; Greiner, J.; Schady, P.; Elliott, J.; Sudilovsky, V.; Krühler, T.; van der Horst, A. J.; Bolmer, J.; Knust, F.; Agurto, C.; Azagra, F.; Belloche, A.; Bertoldi, F.; De Breuck, C.; Delvaux, C.; Filgas, R.; Graham, J. F.; Kann, D. A.; Klose, S.; Menten, K. M.; Nicuesa Guelbenzu, A.; Rau, A.; Rossi, A.; Schmidl, S.; Schuller, F.; Schweyer, T.; Tanga, M.; Weiss, A.; Wiseman, P.; Wyrowski, F.

In: Astronomy & Astrophysics, Vol. 589, A37, 01.05.2016, p. A37.

Research output: Contribution to journalArticle

Varela, K, van Eerten, H, Greiner, J, Schady, P, Elliott, J, Sudilovsky, V, Krühler, T, van der Horst, AJ, Bolmer, J, Knust, F, Agurto, C, Azagra, F, Belloche, A, Bertoldi, F, De Breuck, C, Delvaux, C, Filgas, R, Graham, JF, Kann, DA, Klose, S, Menten, KM, Nicuesa Guelbenzu, A, Rau, A, Rossi, A, Schmidl, S, Schuller, F, Schweyer, T, Tanga, M, Weiss, A, Wiseman, P & Wyrowski, F 2016, 'Microphysics and dynamics of the gamma-ray burst 121024A', Astronomy & Astrophysics, vol. 589, A37, pp. A37. https://doi.org/10.1051/0004-6361/201526260, https://doi.org/10.1051/0004-6361/201526260
Varela, K. ; van Eerten, H. ; Greiner, J. ; Schady, P. ; Elliott, J. ; Sudilovsky, V. ; Krühler, T. ; van der Horst, A. J. ; Bolmer, J. ; Knust, F. ; Agurto, C. ; Azagra, F. ; Belloche, A. ; Bertoldi, F. ; De Breuck, C. ; Delvaux, C. ; Filgas, R. ; Graham, J. F. ; Kann, D. A. ; Klose, S. ; Menten, K. M. ; Nicuesa Guelbenzu, A. ; Rau, A. ; Rossi, A. ; Schmidl, S. ; Schuller, F. ; Schweyer, T. ; Tanga, M. ; Weiss, A. ; Wiseman, P. ; Wyrowski, F. / Microphysics and dynamics of the gamma-ray burst 121024A. In: Astronomy & Astrophysics. 2016 ; Vol. 589. pp. A37.
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abstract = "Aims. The aim of the study is to constrain the physics of gamma-ray bursts (GRBs) by analysing the multi-wavelength afterglow data set of GRB 121024A that covers the full range from radio to X-rays. Methods. Using multi-epoch broad-band observations of the GRB 121024A afterglow, we measured the three characteristic break frequencies of the synchrotron spectrum. We used six epochs of combined XRT and GROND data to constrain the temporal slopes, the dust extinction, the X-ray absorption, and the spectral slope with high accuracy. Two more epochs of combined data from XRT, GROND, APEX, CARMA, and EVLA were used to set constraints on the break frequencies and therefore on the micro-physical and dynamical parameters. Results. The XRT and GROND light curves show a simultaneous and achromatic break at around 49 ks. As a result, the crossing of the synchrotron cooling break is no suitable explanation for the break in the light curve. The multi-wavelength data allow us to test two plausible scenarios explaining the break: a jet break, and the end of energy injection. The jet-break scenario requires a hard electron spectrum, a very low cooling break frequency, and a non-spreading jet. The energy injection avoids these problems, but requires ϵe > 1 (k = 2), spherical outflow, and ϵB < 10-9. Conclusions. In light of the extreme microphysical parameters required by the energy-injection model, we favour a jet-break scenario where νm < νsa to explain the observations. This scenario gives physically meaningful microphysical parameters, and it also naturally explains the reported detection of linear and circular polarisation.",
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TY - JOUR

T1 - Microphysics and dynamics of the gamma-ray burst 121024A

AU - Varela, K.

AU - van Eerten, H.

AU - Greiner, J.

AU - Schady, P.

AU - Elliott, J.

AU - Sudilovsky, V.

AU - Krühler, T.

AU - van der Horst, A. J.

AU - Bolmer, J.

AU - Knust, F.

AU - Agurto, C.

AU - Azagra, F.

AU - Belloche, A.

AU - Bertoldi, F.

AU - De Breuck, C.

AU - Delvaux, C.

AU - Filgas, R.

AU - Graham, J. F.

AU - Kann, D. A.

AU - Klose, S.

AU - Menten, K. M.

AU - Nicuesa Guelbenzu, A.

AU - Rau, A.

AU - Rossi, A.

AU - Schmidl, S.

AU - Schuller, F.

AU - Schweyer, T.

AU - Tanga, M.

AU - Weiss, A.

AU - Wiseman, P.

AU - Wyrowski, F.

PY - 2016/5/1

Y1 - 2016/5/1

N2 - Aims. The aim of the study is to constrain the physics of gamma-ray bursts (GRBs) by analysing the multi-wavelength afterglow data set of GRB 121024A that covers the full range from radio to X-rays. Methods. Using multi-epoch broad-band observations of the GRB 121024A afterglow, we measured the three characteristic break frequencies of the synchrotron spectrum. We used six epochs of combined XRT and GROND data to constrain the temporal slopes, the dust extinction, the X-ray absorption, and the spectral slope with high accuracy. Two more epochs of combined data from XRT, GROND, APEX, CARMA, and EVLA were used to set constraints on the break frequencies and therefore on the micro-physical and dynamical parameters. Results. The XRT and GROND light curves show a simultaneous and achromatic break at around 49 ks. As a result, the crossing of the synchrotron cooling break is no suitable explanation for the break in the light curve. The multi-wavelength data allow us to test two plausible scenarios explaining the break: a jet break, and the end of energy injection. The jet-break scenario requires a hard electron spectrum, a very low cooling break frequency, and a non-spreading jet. The energy injection avoids these problems, but requires ϵe > 1 (k = 2), spherical outflow, and ϵB < 10-9. Conclusions. In light of the extreme microphysical parameters required by the energy-injection model, we favour a jet-break scenario where νm < νsa to explain the observations. This scenario gives physically meaningful microphysical parameters, and it also naturally explains the reported detection of linear and circular polarisation.

AB - Aims. The aim of the study is to constrain the physics of gamma-ray bursts (GRBs) by analysing the multi-wavelength afterglow data set of GRB 121024A that covers the full range from radio to X-rays. Methods. Using multi-epoch broad-band observations of the GRB 121024A afterglow, we measured the three characteristic break frequencies of the synchrotron spectrum. We used six epochs of combined XRT and GROND data to constrain the temporal slopes, the dust extinction, the X-ray absorption, and the spectral slope with high accuracy. Two more epochs of combined data from XRT, GROND, APEX, CARMA, and EVLA were used to set constraints on the break frequencies and therefore on the micro-physical and dynamical parameters. Results. The XRT and GROND light curves show a simultaneous and achromatic break at around 49 ks. As a result, the crossing of the synchrotron cooling break is no suitable explanation for the break in the light curve. The multi-wavelength data allow us to test two plausible scenarios explaining the break: a jet break, and the end of energy injection. The jet-break scenario requires a hard electron spectrum, a very low cooling break frequency, and a non-spreading jet. The energy injection avoids these problems, but requires ϵe > 1 (k = 2), spherical outflow, and ϵB < 10-9. Conclusions. In light of the extreme microphysical parameters required by the energy-injection model, we favour a jet-break scenario where νm < νsa to explain the observations. This scenario gives physically meaningful microphysical parameters, and it also naturally explains the reported detection of linear and circular polarisation.

KW - X-rays: bursts, gamma-ray burst: general, gamma-ray burst: individual: GRB 121024A, methods: observational, radiation mechanisms: non-thermal, stars: jets

UR - http://doi.org/10.1051/0004-6361/201526260

U2 - 10.1051/0004-6361/201526260

DO - 10.1051/0004-6361/201526260

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SN - 0004-6361

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