Optical and near-infrared observations of the GRB020405 afterglow

N. Masetti, E. Palazzi, E. Pian, A. Simoncelli, L. K. Hunt, E. Maiorano, A. Levan, L. Christensen, E. Rol, S. Savaglio, R. Falomo, A. J. Castro-Tirado, J. Hjorth, A. Delsanti, M. Pannella, V. Mohan, S. B. Pandey, R. Sagar, L. Amati, I. BurudJ. M. Castro Cerón, F. Frontera, A. S. Fruchter, J. P U Fynbo, J. Gorosabel, L. Kaper, S. Klose, C. Kouveliotou, L. Nicastro, H. Pedersen, J. Rhoads, I. Salamanca, N. Tanvir, P. M. Vreeswijk, R. A M J Wijers, E. P J Van Den Heuvel

Research output: Contribution to journalArticle

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Abstract

We report on photometric, spectroscopic and polarimetric monitoring of the optical and near-infrared (NIR) afterglow of GRB020405. Ground-based optical observations, performed with 8 different telescopes, started about 1 day after the high-energy prompt event and spanned a period of ∼10 days; the addition of archival HST data extended the coverage up to ∼150 days after the GRB. We report the first detection of the afterglow in NIR bands. The detection of Balmer and oxygen emission lines in the optical spectrum of the host galaxy indicates that the GRB is located at redshift z = 0.691. Fe II and Mg II absorption systems are detected at z = 0.691 and at z = 0.472 in the afterglow optical spectrum. The latter system is likely caused by absorbing clouds in the galaxy complex located ∼2″ southwest of the GRB020405 host. Hence, for the first time, the galaxy responsible for an intervening absorption line system in the spectrum of a GRB afterglow is spectroscopically identified. Optical and NIR photometry of the afterglow indicates that, between 1 and 10 days after the GRB, the decay in all bands is consistent with a single power law of index α = 1.54 ± 0.06. The late-epoch VLT J-band and HST optical points lie above the extrapolation of this power law, so that a plateau (or "bump") is apparent in the VRIJ light curves at 10-20 days after the GRB. The light curves at epochs later than day ∼20 after the GRB are consistent with a power-law decay with index α′ = 1.85 ± 0.15. While other authors have proposed to reproduce the bump with the template of the supernova (SN) 1998bw, considered the prototypical "hypernova", we suggest that it can also be modeled with a SN having the same temporal profile as the other proposed hypernova SN2002ap, but 1.3 mag brighter at peak, and located at the GRB redshift. Alternatively, a shock re-energization may be responsible for the rebrightening. A single polarimetric R-band measurement shows that the afterglow is polarized, with P = 1.5 ± 0.4% and polarization angle θ = 172° ± 8°. Broad-band optical-NIR spectral flux distributions show, in the first days after the GRB, a change of slope across the J band which we interpret as due to the presence of the electron cooling frequency vc. The analysis of the multiwavelength spectrum within the standard fireball model suggests that a population of relativistic electrons with index p ∼ 2.7 produces the optical-NIR emission via synchrotron radiation in an adiabatically expanding blastwave, with negligible host galaxy extinction, and the X-rays via Inverse Compton scattering off lower-frequency afterglow photons.

Original languageEnglish (US)
Pages (from-to)465-481
Number of pages17
JournalAstronomy and Astrophysics
Volume404
Issue number2
StatePublished - Jun 2003
Externally publishedYes

Fingerprint

afterglows
near infrared
power law
galaxies
light curve
electron
supernovae
optical spectrum
time measurement
infrared photometry
fireballs
polarization
decay
extinction
scattering
plateau
cooling
oxygen
extrapolation
plateaus

Keywords

  • Cosmology: observations
  • Gamma rays: burst
  • Line: identification
  • Radiation mechanism: non-thermal

ASJC Scopus subject areas

  • Space and Planetary Science

Cite this

Masetti, N., Palazzi, E., Pian, E., Simoncelli, A., Hunt, L. K., Maiorano, E., ... Van Den Heuvel, E. P. J. (2003). Optical and near-infrared observations of the GRB020405 afterglow. Astronomy and Astrophysics, 404(2), 465-481.

Optical and near-infrared observations of the GRB020405 afterglow. / Masetti, N.; Palazzi, E.; Pian, E.; Simoncelli, A.; Hunt, L. K.; Maiorano, E.; Levan, A.; Christensen, L.; Rol, E.; Savaglio, S.; Falomo, R.; Castro-Tirado, A. J.; Hjorth, J.; Delsanti, A.; Pannella, M.; Mohan, V.; Pandey, S. B.; Sagar, R.; Amati, L.; Burud, I.; Castro Cerón, J. M.; Frontera, F.; Fruchter, A. S.; Fynbo, J. P U; Gorosabel, J.; Kaper, L.; Klose, S.; Kouveliotou, C.; Nicastro, L.; Pedersen, H.; Rhoads, J.; Salamanca, I.; Tanvir, N.; Vreeswijk, P. M.; Wijers, R. A M J; Van Den Heuvel, E. P J.

In: Astronomy and Astrophysics, Vol. 404, No. 2, 06.2003, p. 465-481.

Research output: Contribution to journalArticle

Masetti, N, Palazzi, E, Pian, E, Simoncelli, A, Hunt, LK, Maiorano, E, Levan, A, Christensen, L, Rol, E, Savaglio, S, Falomo, R, Castro-Tirado, AJ, Hjorth, J, Delsanti, A, Pannella, M, Mohan, V, Pandey, SB, Sagar, R, Amati, L, Burud, I, Castro Cerón, JM, Frontera, F, Fruchter, AS, Fynbo, JPU, Gorosabel, J, Kaper, L, Klose, S, Kouveliotou, C, Nicastro, L, Pedersen, H, Rhoads, J, Salamanca, I, Tanvir, N, Vreeswijk, PM, Wijers, RAMJ & Van Den Heuvel, EPJ 2003, 'Optical and near-infrared observations of the GRB020405 afterglow', Astronomy and Astrophysics, vol. 404, no. 2, pp. 465-481.
Masetti N, Palazzi E, Pian E, Simoncelli A, Hunt LK, Maiorano E et al. Optical and near-infrared observations of the GRB020405 afterglow. Astronomy and Astrophysics. 2003 Jun;404(2):465-481.
Masetti, N. ; Palazzi, E. ; Pian, E. ; Simoncelli, A. ; Hunt, L. K. ; Maiorano, E. ; Levan, A. ; Christensen, L. ; Rol, E. ; Savaglio, S. ; Falomo, R. ; Castro-Tirado, A. J. ; Hjorth, J. ; Delsanti, A. ; Pannella, M. ; Mohan, V. ; Pandey, S. B. ; Sagar, R. ; Amati, L. ; Burud, I. ; Castro Cerón, J. M. ; Frontera, F. ; Fruchter, A. S. ; Fynbo, J. P U ; Gorosabel, J. ; Kaper, L. ; Klose, S. ; Kouveliotou, C. ; Nicastro, L. ; Pedersen, H. ; Rhoads, J. ; Salamanca, I. ; Tanvir, N. ; Vreeswijk, P. M. ; Wijers, R. A M J ; Van Den Heuvel, E. P J. / Optical and near-infrared observations of the GRB020405 afterglow. In: Astronomy and Astrophysics. 2003 ; Vol. 404, No. 2. pp. 465-481.
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abstract = "We report on photometric, spectroscopic and polarimetric monitoring of the optical and near-infrared (NIR) afterglow of GRB020405. Ground-based optical observations, performed with 8 different telescopes, started about 1 day after the high-energy prompt event and spanned a period of ∼10 days; the addition of archival HST data extended the coverage up to ∼150 days after the GRB. We report the first detection of the afterglow in NIR bands. The detection of Balmer and oxygen emission lines in the optical spectrum of the host galaxy indicates that the GRB is located at redshift z = 0.691. Fe II and Mg II absorption systems are detected at z = 0.691 and at z = 0.472 in the afterglow optical spectrum. The latter system is likely caused by absorbing clouds in the galaxy complex located ∼2″ southwest of the GRB020405 host. Hence, for the first time, the galaxy responsible for an intervening absorption line system in the spectrum of a GRB afterglow is spectroscopically identified. Optical and NIR photometry of the afterglow indicates that, between 1 and 10 days after the GRB, the decay in all bands is consistent with a single power law of index α = 1.54 ± 0.06. The late-epoch VLT J-band and HST optical points lie above the extrapolation of this power law, so that a plateau (or {"}bump{"}) is apparent in the VRIJ light curves at 10-20 days after the GRB. The light curves at epochs later than day ∼20 after the GRB are consistent with a power-law decay with index α′ = 1.85 ± 0.15. While other authors have proposed to reproduce the bump with the template of the supernova (SN) 1998bw, considered the prototypical {"}hypernova{"}, we suggest that it can also be modeled with a SN having the same temporal profile as the other proposed hypernova SN2002ap, but 1.3 mag brighter at peak, and located at the GRB redshift. Alternatively, a shock re-energization may be responsible for the rebrightening. A single polarimetric R-band measurement shows that the afterglow is polarized, with P = 1.5 ± 0.4{\%} and polarization angle θ = 172° ± 8°. Broad-band optical-NIR spectral flux distributions show, in the first days after the GRB, a change of slope across the J band which we interpret as due to the presence of the electron cooling frequency vc. The analysis of the multiwavelength spectrum within the standard fireball model suggests that a population of relativistic electrons with index p ∼ 2.7 produces the optical-NIR emission via synchrotron radiation in an adiabatically expanding blastwave, with negligible host galaxy extinction, and the X-rays via Inverse Compton scattering off lower-frequency afterglow photons.",
keywords = "Cosmology: observations, Gamma rays: burst, Line: identification, Radiation mechanism: non-thermal",
author = "N. Masetti and E. Palazzi and E. Pian and A. Simoncelli and Hunt, {L. K.} and E. Maiorano and A. Levan and L. Christensen and E. Rol and S. Savaglio and R. Falomo and Castro-Tirado, {A. J.} and J. Hjorth and A. Delsanti and M. Pannella and V. Mohan and Pandey, {S. B.} and R. Sagar and L. Amati and I. Burud and {Castro Cer{\'o}n}, {J. M.} and F. Frontera and Fruchter, {A. S.} and Fynbo, {J. P U} and J. Gorosabel and L. Kaper and S. Klose and C. Kouveliotou and L. Nicastro and H. Pedersen and J. Rhoads and I. Salamanca and N. Tanvir and Vreeswijk, {P. M.} and Wijers, {R. A M J} and {Van Den Heuvel}, {E. P J}",
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TY - JOUR

T1 - Optical and near-infrared observations of the GRB020405 afterglow

AU - Masetti, N.

AU - Palazzi, E.

AU - Pian, E.

AU - Simoncelli, A.

AU - Hunt, L. K.

AU - Maiorano, E.

AU - Levan, A.

AU - Christensen, L.

AU - Rol, E.

AU - Savaglio, S.

AU - Falomo, R.

AU - Castro-Tirado, A. J.

AU - Hjorth, J.

AU - Delsanti, A.

AU - Pannella, M.

AU - Mohan, V.

AU - Pandey, S. B.

AU - Sagar, R.

AU - Amati, L.

AU - Burud, I.

AU - Castro Cerón, J. M.

AU - Frontera, F.

AU - Fruchter, A. S.

AU - Fynbo, J. P U

AU - Gorosabel, J.

AU - Kaper, L.

AU - Klose, S.

AU - Kouveliotou, C.

AU - Nicastro, L.

AU - Pedersen, H.

AU - Rhoads, J.

AU - Salamanca, I.

AU - Tanvir, N.

AU - Vreeswijk, P. M.

AU - Wijers, R. A M J

AU - Van Den Heuvel, E. P J

PY - 2003/6

Y1 - 2003/6

N2 - We report on photometric, spectroscopic and polarimetric monitoring of the optical and near-infrared (NIR) afterglow of GRB020405. Ground-based optical observations, performed with 8 different telescopes, started about 1 day after the high-energy prompt event and spanned a period of ∼10 days; the addition of archival HST data extended the coverage up to ∼150 days after the GRB. We report the first detection of the afterglow in NIR bands. The detection of Balmer and oxygen emission lines in the optical spectrum of the host galaxy indicates that the GRB is located at redshift z = 0.691. Fe II and Mg II absorption systems are detected at z = 0.691 and at z = 0.472 in the afterglow optical spectrum. The latter system is likely caused by absorbing clouds in the galaxy complex located ∼2″ southwest of the GRB020405 host. Hence, for the first time, the galaxy responsible for an intervening absorption line system in the spectrum of a GRB afterglow is spectroscopically identified. Optical and NIR photometry of the afterglow indicates that, between 1 and 10 days after the GRB, the decay in all bands is consistent with a single power law of index α = 1.54 ± 0.06. The late-epoch VLT J-band and HST optical points lie above the extrapolation of this power law, so that a plateau (or "bump") is apparent in the VRIJ light curves at 10-20 days after the GRB. The light curves at epochs later than day ∼20 after the GRB are consistent with a power-law decay with index α′ = 1.85 ± 0.15. While other authors have proposed to reproduce the bump with the template of the supernova (SN) 1998bw, considered the prototypical "hypernova", we suggest that it can also be modeled with a SN having the same temporal profile as the other proposed hypernova SN2002ap, but 1.3 mag brighter at peak, and located at the GRB redshift. Alternatively, a shock re-energization may be responsible for the rebrightening. A single polarimetric R-band measurement shows that the afterglow is polarized, with P = 1.5 ± 0.4% and polarization angle θ = 172° ± 8°. Broad-band optical-NIR spectral flux distributions show, in the first days after the GRB, a change of slope across the J band which we interpret as due to the presence of the electron cooling frequency vc. The analysis of the multiwavelength spectrum within the standard fireball model suggests that a population of relativistic electrons with index p ∼ 2.7 produces the optical-NIR emission via synchrotron radiation in an adiabatically expanding blastwave, with negligible host galaxy extinction, and the X-rays via Inverse Compton scattering off lower-frequency afterglow photons.

AB - We report on photometric, spectroscopic and polarimetric monitoring of the optical and near-infrared (NIR) afterglow of GRB020405. Ground-based optical observations, performed with 8 different telescopes, started about 1 day after the high-energy prompt event and spanned a period of ∼10 days; the addition of archival HST data extended the coverage up to ∼150 days after the GRB. We report the first detection of the afterglow in NIR bands. The detection of Balmer and oxygen emission lines in the optical spectrum of the host galaxy indicates that the GRB is located at redshift z = 0.691. Fe II and Mg II absorption systems are detected at z = 0.691 and at z = 0.472 in the afterglow optical spectrum. The latter system is likely caused by absorbing clouds in the galaxy complex located ∼2″ southwest of the GRB020405 host. Hence, for the first time, the galaxy responsible for an intervening absorption line system in the spectrum of a GRB afterglow is spectroscopically identified. Optical and NIR photometry of the afterglow indicates that, between 1 and 10 days after the GRB, the decay in all bands is consistent with a single power law of index α = 1.54 ± 0.06. The late-epoch VLT J-band and HST optical points lie above the extrapolation of this power law, so that a plateau (or "bump") is apparent in the VRIJ light curves at 10-20 days after the GRB. The light curves at epochs later than day ∼20 after the GRB are consistent with a power-law decay with index α′ = 1.85 ± 0.15. While other authors have proposed to reproduce the bump with the template of the supernova (SN) 1998bw, considered the prototypical "hypernova", we suggest that it can also be modeled with a SN having the same temporal profile as the other proposed hypernova SN2002ap, but 1.3 mag brighter at peak, and located at the GRB redshift. Alternatively, a shock re-energization may be responsible for the rebrightening. A single polarimetric R-band measurement shows that the afterglow is polarized, with P = 1.5 ± 0.4% and polarization angle θ = 172° ± 8°. Broad-band optical-NIR spectral flux distributions show, in the first days after the GRB, a change of slope across the J band which we interpret as due to the presence of the electron cooling frequency vc. The analysis of the multiwavelength spectrum within the standard fireball model suggests that a population of relativistic electrons with index p ∼ 2.7 produces the optical-NIR emission via synchrotron radiation in an adiabatically expanding blastwave, with negligible host galaxy extinction, and the X-rays via Inverse Compton scattering off lower-frequency afterglow photons.

KW - Cosmology: observations

KW - Gamma rays: burst

KW - Line: identification

KW - Radiation mechanism: non-thermal

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