HYDRODYNAMIC PROPERTIES of GAMMA-RAY BURST OUTFLOWS DEDUCED from the THERMAL COMPONENT

Asaf Pe'Er; Hugh Barlow; Shane O'Mahony; Raffaella Margutti; Felix Ryde; Josefin Larsson; Davide Lazzati; Mario Livio

doi:10.1088/0004-637X/813/2/127

HYDRODYNAMIC PROPERTIES of GAMMA-RAY BURST OUTFLOWS DEDUCED from the THERMAL COMPONENT

Asaf Pe'Er, Hugh Barlow, Shane O'Mahony, Raffaella Margutti, Felix Ryde, Josefin Larsson, Davide Lazzati, Mario Livio

Research output: Contribution to journal › Article › peer-review

37 Scopus citations

Abstract

We study the properties of a significant thermal emission component that was identified in 47 gamma-ray bursts observed by different instruments. Within the framework of the "fireball" model, we deduce the values of the Lorentz factor Γ, and the acceleration radius, r₀, for these bursts. We find that all the values of Γ in our sample are in the range with . We find a very weak dependence of Γ on the acceleration radius r₀, with α = -0.10 ± 0.09 at the σ = 2.1 confidence level. The values of r₀ span a wide range, cm, with a mean value of cm. This is higher than the gravitational radius of a 10 M_o black hole by a factor of ≈30. We argue that this result provides indirect evidence for jet propagation inside a massive star, and suggests the existence of recollimation shocks that take place close to this radius.

Original language	English
Article number	127
Journal	Astrophysical Journal
Volume	813
Issue number	2
DOIs	https://doi.org/10.1088/0004-637X/813/2/127
State	Published - 10 Nov 2015
Externally published	Yes

Bibliographical note

Publisher Copyright:
© 2015. The American Astronomical Society. All rights reserved..

Funding

Funders	Funder number
National Science Foundation	1066293
Seventh Framework Programme	618499

Keywords

gamma rays: stars
hydrodynamics
methods: data analysis
radiation mechanisms: thermal
radiative transfer

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10.1088/0004-637X/813/2/127

Cite this

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AU - Pe'Er, Asaf

AU - Barlow, Hugh

AU - O'Mahony, Shane

AU - Margutti, Raffaella

AU - Ryde, Felix

AU - Larsson, Josefin

AU - Lazzati, Davide

AU - Livio, Mario

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KW - gamma rays: stars

KW - hydrodynamics

KW - methods: data analysis

KW - radiation mechanisms: thermal

KW - radiative transfer

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HYDRODYNAMIC PROPERTIES of GAMMA-RAY BURST OUTFLOWS DEDUCED from the THERMAL COMPONENT

Abstract

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Keywords

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