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

Physics and Astronomy

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

29 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 (US)
Article number	127
Journal	Astrophysical Journal
Volume	813
Issue number	2
DOIs	https://doi.org/10.1088/0004-637X/813/2/127
State	Published - Nov 10 2015

Keywords

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

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

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

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title = "HYDRODYNAMIC PROPERTIES of GAMMA-RAY BURST OUTFLOWS DEDUCED from the THERMAL COMPONENT",

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 Mo 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.",

keywords = "gamma rays: stars, hydrodynamics, methods: data analysis, radiation mechanisms: thermal, radiative transfer",

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

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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

PY - 2015/11/10

Y1 - 2015/11/10

N2 - 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 Mo 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.

AB - 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 Mo 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.

KW - gamma rays: stars

KW - hydrodynamics

KW - methods: data analysis

KW - radiation mechanisms: thermal

KW - radiative transfer

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VL - 813

JO - Astrophysical Journal

JF - Astrophysical Journal

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ER -

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

Abstract

Keywords

ASJC Scopus subject areas

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