The interpretation and implication of the afterglow of GRB 060218

Fan, Yi‐Zhong; Piran, Tsvi; Xu, D.

doi:10.1088/1475-7516/2006/09/013

Cited by 66 publications

(141 citation statements)

References 45 publications

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“…3a). For r = r • we have n act cbm = 1 particles/cm 3 , as expected for a "canonical GRB" (Ruffini et al 2007a) and in agreement with the apparent absence of a massive stellar wind in the CBM (Soderberg et al 2006b;Fan et al 2006;Li 2007).…”

Section: The Fireshell Fragmentationsupporting

confidence: 87%

“…We recall that at t d a ∼ 10 4 s there is a sudden enhancement in the radio luminosity and there is an optical luminosity dominated by the SN2006aj emission (Campana et al 2006;Soderberg et al 2006b;Fan et al 2006). Although our analysis addresses only the BAT and XRT observations, for r > 10 18 cm corresponding to t d a > 10 4 s the fit of the XRT data implies two new features: 1) a sudden increase of the R factor from R = 1.0 × 10 −11 to R = 1.6 × 10 −6 , corresponding to a significantly more homogeneous effective CBM distribution (see Fig.…”

Section: The Fit Of the Observed Datamentioning

confidence: 94%

“…This definition depends however on the instrumental threshold (see Ruffini et al 2007c, for details). This source is also interesting since it represents a discriminant between existing GRB theories: it has been pointed out by Soderberg et al (2006b) and Fan et al (2006) that it is impossible to explain the X-and radio afterglows within the traditional synchrotron model. They attempted to fit only the late radio data after ∼10 3 s and they attributed the nature of the prompt emission to an as yet undetermined "inner engine" (see Soderberg et al 2006b), possibly a magnetar ).…”

Section: Introductionmentioning

confidence: 99%

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GRB 060218 and GRBs associated with supernovae Ib/c

Dainotti¹,

Bernardini²,

Bianco³

et al. 2007

A&A

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Context. The Swift satellite has given continuous data in the range 0.3-150 keV from 0 s to 10 6 s for GRB 060218 associated with SN2006aj. This Gamma-Ray Burst (GRB) which has an unusually long duration (T 90 ∼ 2100 s) fulfills the Amati relation. These data offer the opportunity to probe theoretical models for GRBs connected with Supernovae (SNe). Aims. We plan to fit the complete γ-and X-ray light curves of this long duration GRB, including the prompt emission, in order to clarify the nature of the progenitors and the astrophysical scenario of the class of GRBs associated with SNe Ib/c. Methods. We apply our "fireshell" model based on the formation of a black hole, giving the relevant references. It is characterized by the precise equations of motion and equitemporal surfaces and by the role of thermal emission. Results. The initial total energy of the electron-positron plasma E tot e ± = 2.32 × 10 50 erg has a particularly low value, similar to the other GRBs associated with SNe. For the first time, we observe a baryon loading B = 10 −2 which coincides with the upper limit for the dynamical stability of the fireshell. The effective CircumBurst Medium (CBM) density shows a radial dependence n cbm ∝ r −α with 1.0 < ∼ α < ∼ 1.7 and monotonically decreases from 1 to 10 −6 particles/cm 3 . This behavior is interpreted as being due to a fragmentation in the fireshell. Analogies with the fragmented density and filling factor characterizing Novae are outlined. The fit presented is particularly significant in view of the complete data set available for GRB 060218 and of the fact that it fulfills the Amati relation. Conclusions. We fit GRB 060218, usually considered as an X-Ray Flash (XRF), as a "canonical GRB" within our theoretical model. The smallest possible black hole, formed by the gravitational collapse of a neutron star in a binary system, is consistent with the especially low energetics of the class of GRBs associated with SNe Ib/c. We provide the first evidence for a fragmentation in the fireshell. This fragmentation is crucial in explaining both the unusually large T 90 and the consequently inferred abnormally low value of the CBM effective density.

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Section: The Fireshell Fragmentationsupporting

confidence: 87%

Section: The Fit Of the Observed Datamentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

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GRB 060218 and GRBs associated with supernovae Ib/c

Dainotti¹,

Bernardini²,

Bianco³

et al. 2007

A&A

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“…A good example is the afterglow of GRB 060218. The inconsistence of the X-ray afterglow flux with the radio afterglow flux and the very steep XRT spectra support here the central engine afterglow hypothesis [8,25]. So far, there are two more candidates GRB 060607A [18] and GRB 070110 [26].…”

Section: Possible Candidates Of Central Engine Afterglowsupporting

confidence: 71%

Central engine afterglow of Gamma-ray Bursts

Fan¹,

Piran²,

Wei³

2008

AIP Conference Proceedings

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Abstract. Before 2004, nearly all GRB afterglow data could be understood in the context of the external shocks model. This situation has changed in the past two years, when it became clear that some afterglow components should be attributed to the activity of the central engine; i.e., the central engine afterglow. We review here the afterglow emission that is directly related to the GRB central engine. Such an interpretation proposed by Katz, Piran & Sari, peculiar in pre-Swift era, has become generally accepted now.Keywords: Gamma-ray: bursts-radiation mechanisms: nonthermal PACS: 98.70.Rz TWO KINDS OF GRB AFTERGLOWSIn the context of standard fireball model of Gamma-ray Bursts (GRBs), the prompt γ−ray emission is powered by internal shocks and the afterglow emission arises due to external shocks (see [21] for a review). In the pre-Swift era, most of the afterglow data was collected hours after the prompt γ−ray emission. These data was found to be consistent with the external forward shock model, though at times energy injection, a wind medium profile, or a structured/patchy jet were needed. We call the emission relevant to the external shocks generated by the GRB remnant as the "fireball afterglow" or "afterglow". An alternative possibility for the production of the afterglow is a continued activity of the central engine (i.e., the central engine afterglow) via either the "internal shocks" or "magnetic dissipation". This idea has been put forward by Katz, Piran & Sari already in 1998, shortly after the discovery of the afterglow of GRB 970228. However, the agreement of the predictions of the external shock afterglow model [24] with most subsequent multi-wavelength afterglows observation strongly disfavors the central engine afterglow interpretation.One disadvantage of the central engine afterglow model is its lack of predictive power. The fireball afterglow model, instead, has predicted smooth light curves and in particular the intrinsic relation between the flux in different bands (e.g., [24]) as well as between the spectral slops and the temporal decay. In 2003, it was already clear that in the case of a fireball afterglow, the variability timescale of the emission δt divided by the occurrence time t has to be in order of 1 or larger [19]. A highly relevant constraint is that the decline of the fireball afterglow emission can not be steeper than t −(2+β ) , (where β is the spectral index) unless the edge of the GRB ejecta is visible. This is because the GRB outflow is curving and emission from high latitude (relative to the observer) will reach us at later

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“…Furthermore, the kinetic energy required to power such an external shock would produce far too much radio. Instead, the X-ray emission might be attributed to a prolonged activity of the central engine (Fan et al 2006;Soderberg et al 2006a). …”

Section: K3mentioning

confidence: 99%

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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The interpretation and implication of the afterglow of GRB 060218

Cited by 66 publications

References 45 publications

GRB 060218 and GRBs associated with supernovae Ib/c

GRB 060218 and GRBs associated with supernovae Ib/c

Central engine afterglow of Gamma-ray Bursts

Gamma-ray burst theory after Swift

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