LOOKING INTO THE FIREBALL: ROTSE-III AND<i>SWIFT</i>OBSERVATIONS OF EARLY GAMMA-RAY BURST AFTERGLOWS

Rykoff, E. S.; Aharonian, F.; Akerlof, C.; Ashley, M. C. B.; Barthelmy, S. D.; Flewelling, H.; Gehrels, N.; Göǧüş, E.; Güver, T.; Kızıloğlu, Ü.; Krimm, H. A.; McKay, Timothy A.; Özel, M. E.; Phillips, A.; Quimby, R.; Rowell, G.; Rujopakarn, W.; Schaefer, Bradley E.; Smith, D. A.; Vestrand, W. T.; Wheeler, J. C.; Wren, J.; Yuan, F.; Yost, S. A.

doi:10.1088/0004-637x/702/1/489

Cited by 105 publications

(130 citation statements)

References 81 publications

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“…This implies that a constant density medium is preferred and the cooling frequency is likely to lie between the X-ray and optical/UV bands at least for a large number of events. This is consistent with recent analyses by Rykoff et al (2009), Oates et al (2011), Schulze et al (2011) and De Pasquale et al (2013) and supports our choice of assumptions in §4 & 5. We note that, while the majority of GRBs in our sample are consistent with lying in a constant density medium, there are a few GRBs that are consistent with lying in a wind-like medium; these are some of the fastest decaying and therefore the brightest GRBs in the sample.…”

Section: Comparison Of Observed and Predicted Correlationssupporting

confidence: 93%

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Exploring the canonical behaviour of long gamma-ray bursts using an intrinsic multiwavelength afterglow correlation

Oates

Racusin

Pasquale

et al. 2015

Mon. Not. R. Astron. Soc.

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In this paper we further investigate the relationship, reported by Oates et al. (2012), between the optical/UV afterglow luminosity (measured at restframe 200 s) and average afterglow decay rate (measured from restframe 200 s onwards) of long duration Gamma-ray Bursts (GRBs). We extend the analysis by examining the X-ray light curves, finding a consistent correlation. We therefore explore how the parameters of these correlations relate to the prompt emission phase and, using a Monte Carlo simulation, explore whether these correlations are consistent with predictions of the standard afterglow model. We find significant correlations between: log L O,200s and log L X,200s ; α O,>200s and α X,>200s , consistent with simulations. The model also predicts relationships between log E iso and log L 200,s , however, while we find such relationships in the observed sample, the slope of the linear regression is shallower than that simulated and inconsistent at 3σ. Simulations also do not agree with correlations observed between log L 200s and α >200s , or log E iso and α >200s . Overall, these observed correlations are consistent with a common underlying physical mechanism producing GRBs and their afterglows regardless of their detailed temporal behaviour. However, a basic afterglow model has difficulty explaining all the observed correlations. This leads us to briefly discuss alternative more complex models.

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Section: Comparison Of Observed and Predicted Correlationssupporting

confidence: 93%

“…Rykoff et al 2009;Oates et al 2009;Schulze et al 2011). Therefore we shall only consider relationships appropriate for this density medium.…”

Section: The Standard Synchrotron Afterglow Modelmentioning

confidence: 98%

Exploring the canonical behaviour of long gamma-ray bursts using an intrinsic multiwavelength afterglow correlation

Oates

Racusin

Pasquale

et al. 2015

Mon. Not. R. Astron. Soc.

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“…The data quality, however, is not always adequate for a detailed modelling, due to the modest aperture of most robotic, rapid-pointing, telescopes. For several events it was possible to detect the afterglow (external shock) onset (Vestrand et al 2006;Molinari et al 2007;Ferrero et al 2009;Rykoff et al 2009;Klotz et al 2009) as predicted by semianalytical estimates (Sari & Piran 1999) and more accurate numerical analyses (Kobayashi & Zhang 2007;Jin & Fan 2007). The lack of reverse shock (see e.g.…”

Section: Introductionmentioning

confidence: 98%

Challenging gamma-ray burst models through the broadband dataset of GRB 060908

Covino¹,

Campana²,

Conciatore

et al. 2010

A&A

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Context. Multiwavelength observations of gamma-ray burst prompt and afterglow emission are a key tool to separate the various possible emission processes and scenarios proposed to interpret the complex gamma-ray burst phenomenology. Aims. We collected a large dataset on GRB 060908 in order to carry out a comprehensive analysis of the prompt emission as well as the early and late afterglow. Methods. Data from Swift-BAT, -XRT and -UVOT together with data from a number of different ground-based optical/near-infrared and millimeter telescopes allowed us to follow the afterglow evolution after about a minute from the high-energy event down to the host galaxy limit. We discuss the physical parameters required to model these emissions. Results. The prompt emission of GRB 060908 was characterised by two main periods of activity, spaced by a few seconds of low intensity, with a tight correlation between activity and spectral hardness. Observations of the afterglow began less than one minute after the high-energy event, when it was already in a decaying phase, and it was characterised by a rather flat optical/near-infrared spectrum which can be interpreted as due to a hard energy-distribution of the emitting electrons. On the other hand, the X-ray spectrum of the afterglow could be fit by a rather soft electron distribution. Conclusions. GRB 060908 is a good example of a gamma-ray burst with a rich multi-wavelength set of observations. The availability of this dataset, built thanks to the joint efforts of many different teams, allowed us to carry out stringent tests for various interpretative scenarios, showing that a satisfactorily modelling of this event is challenging. In the future, similar efforts will enable us to obtain optical/near-infrared coverage comparable in quality and quantity to the X-ray data for more events, therefore opening new avenues to progress gamma-ray burst research.

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“…Observations of rapid temporal variability and extremely high-energy photons require GRBs to have ultra-relativistic motion of their outflow plasma with Lorentz factors at least as high as a few hundred , implying that most of the energy of the burst is in kinetic form. Such large Lorentz factor are also indirectly suggested by the non-observation of neutrinos in coincidence with GRBs (Abbasi et al 2012) and the constraints from the early optical afterglow; see, e.g., Rykoff et al (2009).…”

Section: Introductionmentioning

confidence: 80%

The Anatomy of a Long Gamma-Ray Burst: A Simple Classification Scheme for the Emission Mechanism(s)

Bégué

Burgess

2016

ApJ

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Ultra-relativistic motion and efficient conversion of kinetic energy to radiation are required by gamma-ray burst (GRB) observations, yet they are difficult to simultaneously achieve. Three leading mechanisms have been proposed to explain the observed emission emanating from GRB outflows: radiation from either relativistic internal or external shocks, or thermal emission from a photosphere. Previous works were dedicated to independently treating these three mechanisms and arguing for a sole, unique origin of the prompt emission of GRBs. In contrast, herein, we first explain why all three models are valid mechanisms and that a contribution from each of them is expected in the prompt phase. Additionally, we show that a single parameter, the dimensionless entropy of the GRB outflow, determines which mechanism contributes the most to the emission. More specifically, internal shocks dominate for low values of the dimensionless entropy, external shocks for intermediate values, and finally, photospheric emission for large values. We present a unified framework for the emission mechanisms of GRBs with easily testable predictions for each process.

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LOOKING INTO THE FIREBALL: ROTSE-III ANDSWIFTOBSERVATIONS OF EARLY GAMMA-RAY BURST AFTERGLOWS

Cited by 105 publications

References 81 publications

Exploring the canonical behaviour of long gamma-ray bursts using an intrinsic multiwavelength afterglow correlation

Exploring the canonical behaviour of long gamma-ray bursts using an intrinsic multiwavelength afterglow correlation

Challenging gamma-ray burst models through the broadband dataset of GRB 060908

The Anatomy of a Long Gamma-Ray Burst: A Simple Classification Scheme for the Emission Mechanism(s)

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