Colour variations in the GRB 120327A afterglow

A. Melandri; S. Covino; E. Zaninoni; S. Campana; Jan Bolmer; B. E. Cobb; J. Gorosabel; Jin Wook Kim; N. P. M. Kuin; D. Kuroda; D. Malesani; C. G. Mundell; F. Nappo; B. Sbarufatti; R. J. Smith; I. A. Steele; M. Topinka; A. S. Trotter; F. J. Virgili; M. G. Bernardini; P. D’avanzo; V. D’elia; D. Fugazza; G. Ghirlanda; A. Gomboc; J. Greiner; C. Guidorzi; J. B. Haislip; H. Hanayama; L. Hanlon; M. Im; K. M. Ivarsen; J. Japelj; M. Jelínek; N. Kawai; S. Kobayashi; D. Kopac; A. P. Lacluyzé; A. Martin-carrillo; D Murphy; D. E. Reichart; R. Salvaterra; O. S. Salafia; G. Tagliaferri; S. D. Vergani

doi:10.1051/0004-6361/201731759

Colour variations in the GRB 120327A afterglow

A. Melandri, S. Covino, E. Zaninoni, S. Campana, Jan Bolmer, B. E. Cobb, J. Gorosabel, Jin Wook Kim, N. P. M. Kuin, D. Kuroda, D. Malesani, C. G. Mundell, F. Nappo, B. Sbarufatti, R. J. Smith, I. A. Steele, M. Topinka, A. S. Trotter, F. J. Virgili, M. G. BernardiniP. D’avanzo, V. D’elia, D. Fugazza, G. Ghirlanda, A. Gomboc, J. Greiner, C. Guidorzi, J. B. Haislip, H. Hanayama, L. Hanlon, M. Im, K. M. Ivarsen, J. Japelj, M. Jelínek, N. Kawai, S. Kobayashi, D. Kopac, A. P. Lacluyzé, A. Martin-carrillo, D Murphy, D. E. Reichart, R. Salvaterra, O. S. Salafia, G. Tagliaferri, S. D. Vergani

Department of Physics

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Abstract

Aims. We present a comprehensive temporal and spectral analysis of the long Swift GRB 120327A afterglow data to investigate possible causes of the observed early-time colour variations.

Methods. We collected data from various instruments and telescopes in X-ray, ultraviolet, optical, and near-infrared bands, and determined the shapes of the afterglow early-time light curves. We studied the overall temporal behaviour and the spectral energy distributions from early to late times.

Results. The ultraviolet, optical, and near-infrared light curves can be modelled with a single power-law component between 200 and 2 × 104 s after the burst event. The X-ray light curve shows a canonical steep-shallow-steep behaviour that is typical of long gamma-ray bursts. At early times a colour variation is observed in the ultraviolet/optical bands, while at very late times a hint of a re-brightening is visible. The observed early-time colour change can be explained as a variation in the intrinsic optical spectral index, rather than an evolution of the optical extinction.

Original language	English
Pages (from-to)	A29
Journal	Astronomy & Astrophysics
Volume	607
DOIs	https://doi.org/10.1051/0004-6361/201731759
Publication status	Published - 31 Oct 2017

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Melandri, A., Covino, S., Zaninoni, E., Campana, S., Bolmer, J., Cobb, B. E., Gorosabel, J., Kim, J. W., Kuin, N. P. M., Kuroda, D., Malesani, D., Mundell, C. G., Nappo, F., Sbarufatti, B., Smith, R. J., Steele, I. A., Topinka, M., Trotter, A. S., Virgili, F. J., ... Vergani, S. D. (2017). Colour variations in the GRB 120327A afterglow. Astronomy & Astrophysics, 607, A29. https://doi.org/10.1051/0004-6361/201731759

Melandri, A, Covino, S, Zaninoni, E, Campana, S, Bolmer, J, Cobb, BE, Gorosabel, J, Kim, JW, Kuin, NPM, Kuroda, D, Malesani, D, Mundell, CG, Nappo, F, Sbarufatti, B, Smith, RJ, Steele, IA, Topinka, M, Trotter, AS, Virgili, FJ, Bernardini, MG, D’avanzo, P, D’elia, V, Fugazza, D, Ghirlanda, G, Gomboc, A, Greiner, J, Guidorzi, C, Haislip, JB, Hanayama, H, Hanlon, L, Im, M, Ivarsen, KM, Japelj, J, Jelínek, M, Kawai, N, Kobayashi, S, Kopac, D, Lacluyzé, AP, Martin-carrillo, A, Murphy, D, Reichart, DE, Salvaterra, R, Salafia, OS, Tagliaferri, G & Vergani, SD 2017, 'Colour variations in the GRB 120327A afterglow', Astronomy & Astrophysics, vol. 607, pp. A29. https://doi.org/10.1051/0004-6361/201731759

@article{ebda67bc94b7477ea855d1b8c044704e,

title = "Colour variations in the GRB 120327A afterglow",

abstract = "Aims. We present a comprehensive temporal and spectral analysis of the long Swift GRB 120327A afterglow data to investigate possible causes of the observed early-time colour variations.Methods. We collected data from various instruments and telescopes in X-ray, ultraviolet, optical, and near-infrared bands, and determined the shapes of the afterglow early-time light curves. We studied the overall temporal behaviour and the spectral energy distributions from early to late times.Results. The ultraviolet, optical, and near-infrared light curves can be modelled with a single power-law component between 200 and 2 × 104 s after the burst event. The X-ray light curve shows a canonical steep-shallow-steep behaviour that is typical of long gamma-ray bursts. At early times a colour variation is observed in the ultraviolet/optical bands, while at very late times a hint of a re-brightening is visible. The observed early-time colour change can be explained as a variation in the intrinsic optical spectral index, rather than an evolution of the optical extinction.",

author = "A. Melandri and S. Covino and E. Zaninoni and S. Campana and Jan Bolmer and Cobb, {B. E.} and J. Gorosabel and Kim, {Jin Wook} and Kuin, {N. P. M.} and D. Kuroda and D. Malesani and Mundell, {C. G.} and F. Nappo and B. Sbarufatti and Smith, {R. J.} and Steele, {I. A.} and M. Topinka and Trotter, {A. S.} and Virgili, {F. J.} and Bernardini, {M. G.} and P. D{\textquoteright}avanzo and V. D{\textquoteright}elia and D. Fugazza and G. Ghirlanda and A. Gomboc and J. Greiner and C. Guidorzi and Haislip, {J. B.} and H. Hanayama and L. Hanlon and M. Im and Ivarsen, {K. M.} and J. Japelj and M. Jel{\'i}nek and N. Kawai and S. Kobayashi and D. Kopac and Lacluyz{\'e}, {A. P.} and A. Martin-carrillo and D Murphy and Reichart, {D. E.} and R. Salvaterra and Salafia, {O. S.} and G. Tagliaferri and Vergani, {S. D.}",

year = "2017",

month = oct,

day = "31",

doi = "10.1051/0004-6361/201731759",

language = "English",

volume = "607",

pages = "A29",

journal = "Astronomy & Astrophysics",

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TY - JOUR

T1 - Colour variations in the GRB 120327A afterglow

AU - Melandri, A.

AU - Covino, S.

AU - Zaninoni, E.

AU - Campana, S.

AU - Bolmer, Jan

AU - Cobb, B. E.

AU - Gorosabel, J.

AU - Kim, Jin Wook

AU - Kuin, N. P. M.

AU - Kuroda, D.

AU - Malesani, D.

AU - Mundell, C. G.

AU - Nappo, F.

AU - Sbarufatti, B.

AU - Smith, R. J.

AU - Steele, I. A.

AU - Topinka, M.

AU - Trotter, A. S.

AU - Virgili, F. J.

AU - Bernardini, M. G.

AU - D’avanzo, P.

AU - D’elia, V.

AU - Fugazza, D.

AU - Ghirlanda, G.

AU - Gomboc, A.

AU - Greiner, J.

AU - Guidorzi, C.

AU - Haislip, J. B.

AU - Hanayama, H.

AU - Hanlon, L.

AU - Im, M.

AU - Ivarsen, K. M.

AU - Japelj, J.

AU - Jelínek, M.

AU - Kawai, N.

AU - Kobayashi, S.

AU - Kopac, D.

AU - Lacluyzé, A. P.

AU - Martin-carrillo, A.

AU - Murphy, D

AU - Reichart, D. E.

AU - Salvaterra, R.

AU - Salafia, O. S.

AU - Tagliaferri, G.

AU - Vergani, S. D.

PY - 2017/10/31

Y1 - 2017/10/31

N2 - Aims. We present a comprehensive temporal and spectral analysis of the long Swift GRB 120327A afterglow data to investigate possible causes of the observed early-time colour variations.Methods. We collected data from various instruments and telescopes in X-ray, ultraviolet, optical, and near-infrared bands, and determined the shapes of the afterglow early-time light curves. We studied the overall temporal behaviour and the spectral energy distributions from early to late times.Results. The ultraviolet, optical, and near-infrared light curves can be modelled with a single power-law component between 200 and 2 × 104 s after the burst event. The X-ray light curve shows a canonical steep-shallow-steep behaviour that is typical of long gamma-ray bursts. At early times a colour variation is observed in the ultraviolet/optical bands, while at very late times a hint of a re-brightening is visible. The observed early-time colour change can be explained as a variation in the intrinsic optical spectral index, rather than an evolution of the optical extinction.

AB - Aims. We present a comprehensive temporal and spectral analysis of the long Swift GRB 120327A afterglow data to investigate possible causes of the observed early-time colour variations.Methods. We collected data from various instruments and telescopes in X-ray, ultraviolet, optical, and near-infrared bands, and determined the shapes of the afterglow early-time light curves. We studied the overall temporal behaviour and the spectral energy distributions from early to late times.Results. The ultraviolet, optical, and near-infrared light curves can be modelled with a single power-law component between 200 and 2 × 104 s after the burst event. The X-ray light curve shows a canonical steep-shallow-steep behaviour that is typical of long gamma-ray bursts. At early times a colour variation is observed in the ultraviolet/optical bands, while at very late times a hint of a re-brightening is visible. The observed early-time colour change can be explained as a variation in the intrinsic optical spectral index, rather than an evolution of the optical extinction.

U2 - 10.1051/0004-6361/201731759

DO - 10.1051/0004-6361/201731759

M3 - Article

SN - 0004-6361

VL - 607

SP - A29

JO - Astronomy & Astrophysics

JF - Astronomy & Astrophysics

ER -

Colour variations in the GRB 120327A afterglow

Abstract

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