Optical Follow-Up of GRB 970508

Galama, T. J.; Groot, P.; Paradijs, J. van; Kouveliotou, C.; Strom, R. G.; Wijers, R. A. M. J.; Tanvir, N. R.; Bloom, J.; Centurión, M.; Telting, J. H.; Rutten, R. G. M.; Smith, Paul S.; Mackey, C.; Smartt, S. J.; Benn, Chris; Heise, J.; Zand, J. in ’t

doi:10.1086/311268

Cited by 94 publications

(92 citation statements)

References 21 publications

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“…Although such late brightenings or flares are not unprecedented, only a few bursts have exhibited them so far: e.g. GRB 970508 (Piro et al 1998;Galama et al 1998), the short GRB 050724 (Campana et al 2006;Malesani et al 2007), the z = 6.3 GRB 050904 (Cusumano et al 2007;Watson et al 2006). We also note the presence of the shallow decay phase preceding the X-ray brightening (or corresponding to its gradual onset).…”

Section: Discussionmentioning

confidence: 60%

GRB 070311: a direct link between the prompt emission and the afterglow

Guidorzi

Vergani

Sazonov

et al. 2007

A&A

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Context. The prompt emission of gamma-ray bursts is mostly thought to be produced in internal shocks of relativistic shells emitted by the progenitor at different times, whereas the late multi-band afterglow is interpreted as the synchrotron emission of electrons swept up by the fireball expanding through the surrounding interstellar medium. The short timescale variability observed in flares superimposed on the X-ray/optical afterglow of several bursts, recently made possible by Swift, has been interpreted as evidence for prolonged activity of the inner engine through internal shocks. Yet, it is not clear whether this applies to all the observed bursts and, in particular, whether the bursts exhibiting single γ-ray pulses with no short timescale variability at late times could also be entirely interpreted as external shocks. Aims. We present prompt γ-ray, early NIR/optical, late optical and X-ray observations of the peculiar GRB 070311 discovered by INTEGRAL, in order to gain clues on the mechanisms responsible for the prompt γ-ray pulse as well as for the early and late multiband afterglow of GRB 070311. Methods. We fitted with empirical functions the gamma-ray and optical light curves and scaled the result to the late time X-rays. Results. The H-band light curve taken by REM shows two pulses peaking 80 and 140 s after the peak of the γ-ray burst and possibly accompanied by a faint γ-ray tail. Remarkably, the late optical and X-ray afterglow underwent a major rebrightening between 3 × 10 4 and 2 × 10 5 s after the burst with an X-ray fluence comparable with that of the prompt emission extrapolated in the same band. Notably, the time profile of the late rebrightening can be described as the combination of a time-rescaled version of the prompt γ-ray pulse and an underlying power law. Conclusions. This result supports a common origin for both prompt and late X-ray/optical afterglow rebrightening of GRB 070311 within the external shock scenario. The main fireball would be responsible for the prompt emission, while a second shell would produce the rebrightening when impacting the leading blastwave in a refreshed shock.

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Section: Discussionmentioning

confidence: 60%

GRB 070311: a direct link between the prompt emission and the afterglow

Guidorzi

Vergani

Sazonov

et al. 2007

A&A

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“…-GRB afterglows decline faster than t −1 and do not contribute significantly to the total energy budget (Galama et al 1998). However, it is possible that the adiabatic regime of the shock deceleration persists for a very long time, so that the bulk of GRB energy has never been observed.…”

Section: A Major Part Of the Fireball Kinetic Energy Is Con-mentioning

confidence: 99%

Physical parameters and emission mechanism in gamma-ray bursts

Derishev

Kocharovsky

2001

A&A

107

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Abstract. Detailed information on the physical parameters in the sources of cosmological Gamma-Ray Bursts (GRBs) is obtained from few plausible assumptions consistent with observations. We consider monoenergetic injection of electrons and let them cool self-consistently, taking into account Klein-Nishina cut-off in electronphoton scattering. The general requirements posed by the assumptions on the emission mechanism in GRBs are formulated. It is found that the observed radiation in the sub-MeV energy range is generated by the synchrotron emission mechanism, though about ten per cent of the total GRB energy should be converted via the inverse Compton (IC) process into the ultra-hard spectral domain (above 100 GeV). We estimate the magnetic field strength in the emitting region, the Lorentz factor of accelerated electrons, and the typical energy of IC photons. We show that there is a synchrotron-self-Compton constraint which limits the parameter space available for GRBs that are radiatively efficient in the sub-MeV domain. This concept is analogous to the line-of-death relation existing for pulsars and allows us to derive the lower limits on both GRB duration and the timescale of GRB variability. The upper limit on the Lorentz factor of GRB fireballs is also found. We demonstrate that steady-state electron distribution consistent with the Compton losses may produce different spectral indices, e.g., 3/4 as opposed to the figure 1/2 widely discussed in the literature. It is suggested that the changes in the decline rate observed in the lightcurves of several GRB afterglows may be due to either a transition to efficient IC cooling or the time evolution of Klein-Nishina and/or Compton spectral breaks, which are the general features of self-consistent electron distribution.

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“…Optical observations of afterglows (e.g., GRB 970228: Groot et al 1997;van Paradijs et al 1997) have allowed redshifts to be measured for a number of GRBs (e.g., GRB 970508: Metzger et al 1997), providing definitive proof of their cosmological origin. GRB 980425 was likely associated with SN 1998bw, and this was the first direct evidence that at least some GRBs result from the core collapse of massive stars (Galama et al 1998). However, the isotropic energy of that burst was 10 Ϫ3 to 10 Ϫ4 times weaker (Woosley, Eastman, & Schmidt 1999) than classical cosmological GRBs, which placed it in a unique class.…”

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confidence: 95%

Spectroscopic Discovery of the Supernova 2003dh Associated with GRB 030329

Stanek

Matheson

Garnavich

et al. 2003

ApJ

1,180

1,052

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We present early observations of the afterglow of GRB 030329 and the spectroscopic discovery of its associated supernova SN 2003dh. We obtained spectra of the afterglow of GRB 030329 each night from March 30.12 (0.6 days after the burst) to April 8.13 (UT) (9.6 days after the burst). The spectra cover a wavelength range of 350-850 nm. The early spectra consist of a power-law continuum ( ) with narrow emission lines orig-Ϫ0.9

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Optical Follow-Up of GRB 970508

Cited by 94 publications

References 21 publications

GRB 070311: a direct link between the prompt emission and the afterglow

GRB 070311: a direct link between the prompt emission and the afterglow

Physical parameters and emission mechanism in gamma-ray bursts

Spectroscopic Discovery of the Supernova 2003dh Associated with GRB 030329

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