What did ASCA see in the GRB 970828 afterglow?

Yoshida, A.; Namiki, M.; Otani, Chiko; Kawai, N.; Murakami, T.; Ueda, Yoshihiro; Shibata, Ryo; Uno, S.

doi:10.1051/aas:1999297

Cited by 91 publications

(83 citation statements)

References 1 publication

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“…Due to their large Doppler shift δ, the hydrogen emission lines (and the emission lines from the swept up ISM and supernova shell material) as well as the CB's thermal bremsstrahlung, are shifted to the observer's X-ray band. They contribute significantly to the X-ray afterglow and may provide a simple alternative explanation (Dar & De Rújula 2000) to the commonly assumed Fe-line origin of the X-ray lines observed in the afterglows of GRB 970508: Piro et al (1998), GRB 970828: Yoshida et al (1999;2001), GRB 991216: Piro et al (2000) and GRB 000214: Antonelli et al (2000).…”

Section: Discussionmentioning

confidence: 93%

On the radio afterglow of gamma ray bursts

Dado

Dar

Rújula

2003

A&A

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Abstract. We use the cannonball (CB) model of gamma ray bursts (GRBs) to predict the spectral and temporal behaviour of their radio afterglows (AGs). A single simple expression describes the AGs at all times and frequencies; its high-frequency limit reproduces the successful CB model predictions for optical and X-ray AGs. We analyze all of the observed radio AGs of GRBs with known redshifts, including those of the exceptionally close-by GRB 980425. We also study in detail the timeevolution of the AGs' spectral index. The agreement between theory and observations is excellent, even though the CB model is extremely frugal in the number of parameters required to explain the radio observations. We propose to use the scintillations in the radio AGs of GRBs to verify and measure the hyperluminal speed of their jetted CBs, whose apparent angular velocity is of the same order of magnitude as that of galactic pulsars, consistently measured directly, or via scintillations.

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Section: Discussionmentioning

confidence: 93%

On the radio afterglow of gamma ray bursts

Dado

Dar

Rújula

2003

A&A

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“…(c ) The X-ray flares Energetic X-ray flares have been detected in several pre-Swift GRBs (Piro et al 1998b;Yoshida et al 1999;Piro et al 2005;Galli & Piro 2006) and in about a half of Swift GRBs (Burrows et al 2005;O'Brien et al 2006). It was thought earlier that these flares might be related to a delayed onset of the forward shock (Piro et al 2005;Galli & Piro 2006).…”

Section: K3mentioning

confidence: 99%

“…Flares were seen already by BeppoSAX (Piro et al 1998a(Piro et al , 2005Galli & Piro 2006) and even by ASCA (Yoshida et al 1999). However, their real extent was realized only with Swift (Burrows et al 2005;Falcone et al 2006;O'Brien et al 2006).…”

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confidence: 97%

Gamma-ray burst theory after Swift

Piran

Fan

2007

Phil. Trans. R. Soc. A.

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Afterglow observations in the pre-Swift era confirmed to a large extend the relativistic blast wave model for gamma-ray bursts (GRBs). Together with the observations of properties of host galaxies and the association with (type Ic) SNe, this has led to the generally accepted collapsar origin of long GRBs. However, most of the afterglow data was collected hours after the burst. The X-ray telescope and the UV/optical telescope onboard Swift are able to slew to the direction of a burst in real time and record the early broadband afterglow light curves. These observations, and in particular the X-ray observations, resulted in many surprises. While we have anticipated a smooth transition from the prompt emission to the afterglow, many observed that early light curves are drastically different. We review here how these observations are changing our understanding of GRBs.

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“…INTRODUCTION The detection of spectral signatures associated with the environment of a g-ray burst (GRB) would provide important clues about the triggering mechanism and the progenitor (Mészáros & Rees 1998;Lazzati, Campana, & Ghisellini 1999;Böttcher 2000). Observations with Chandra, ASCA, and BeppoSAX have provided tentative evidence for Fe Ka line and edge features in at least five bursts; GRB 970508 (Piro et al 1999), GRB 970828 (Yoshida et al 1999), GRB 991216 (Piro et al 2000), and GRB 000214 (Antonelli et al 2000) all show an emission feature during the X-ray afterglow a few hours to a day after the burst event, while GRB 990705 (Amati et al 2000) displays a prominent X-ray absorption feature during the burst itself. Although most of the line detections are only marginally significant and fail to distinguish between the various line excitation mechanisms, 1 GRB 991216 shows a keV line at a mod-3.49 ‫ע‬ 0.06 erate confidence level (∼4 j).…”

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confidence: 99%

Iron Kα Emission from X-Ray Reflection: Predictions for Gamma-Ray Burst Models

Ballantyne¹,

Ramírez-Ruiz²

2001

The Astrophysical Journal

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Recent observations of several g-ray burst (GRB) afterglows have shown evidence for a large amount of X-ray line-emitting material, possibly arising from ionized iron. A significant detection of an X-ray spectral feature, such as that found in the Chandra observation of GRB 991216, may provide important constraints on the immediate environment of the burst and hence on progenitor models. The large Fe Ka equivalent widths inferred from the X-ray observations favor models in which the line is produced when the primary X-ray emission from the source strikes Thomson-thick material and Compton scatters into our line of sight. We present such reflection spectra here, computed in a fully self-consistent manner, and discuss the range of ionization parameters that may be relevant to different models of GRBs. We argue that the presence of a strong hydrogen-like Ka line is unlikely, because Fe xxvi photons would be trapped resonantly and removed from the line core by Compton scattering. In contrast, a strong narrow emission line from He-like Fe xxv is prominent in the model spectra. We briefly discuss how these constraints may affect the line energy determination in GRB 991216.

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What did ASCA see in the GRB 970828 afterglow?

Cited by 91 publications

References 1 publication

On the radio afterglow of gamma ray bursts

On the radio afterglow of gamma ray bursts

Gamma-ray burst theory after Swift

Iron Kα Emission from X-Ray Reflection: Predictions for Gamma-Ray Burst Models

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