Chromatic signatures in the microlensing of gamma-ray burst afterglows

Jonathan Granot; Abraham Loeb

doi:10.1086/319843

Chromatic signatures in the microlensing of gamma-ray burst afterglows

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

Abstract

We calculate the radial surface brightness profile of the image of a gamma-ray burst (GRB) afterglow. The afterglow spectrum consists of several power-law segments separated by breaks. The image profile changes considerably across each of the spectral breaks. It also depends on the density profile of the ambient medium into which the GRB fireball propagates. Gravitational microlensing by an intervening star can resolve the afterglow image. We calculate the predicted magnification history of GRB afterglows as a function of observed frequency and ambient medium properties. We find that intensive monitoring of a microlensed afterglow light curve can be used to reconstruct the parameters of the fireball and its environment and provide constraints on particle acceleration and magnetic field amplification in relativistic blast waves.

Original language	English
Pages (from-to)	L63-L66
Journal	Astrophysical Journal
Volume	551
Issue number	1 PART 2
DOIs	https://doi.org/10.1086/319843
State	Published - 10 Apr 2001
Externally published	Yes

Bibliographical note

Funding Information:
This work was supported in part by the Horowitz foundation and the US-Israel BSF grant BSF-9800225 (for J. G.) and by NASA grants NAG5-7039 and NAG5-7768, NSF grants AST 99-00877 and AST 00-71019, and US-Israel BSF grant BSF-9800343 (for A. L.).

Keywords

Gamma rays: bursts
Gravitational lensing

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10.1086/319843

Cite this

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title = "Chromatic signatures in the microlensing of gamma-ray burst afterglows",

abstract = "We calculate the radial surface brightness profile of the image of a gamma-ray burst (GRB) afterglow. The afterglow spectrum consists of several power-law segments separated by breaks. The image profile changes considerably across each of the spectral breaks. It also depends on the density profile of the ambient medium into which the GRB fireball propagates. Gravitational microlensing by an intervening star can resolve the afterglow image. We calculate the predicted magnification history of GRB afterglows as a function of observed frequency and ambient medium properties. We find that intensive monitoring of a microlensed afterglow light curve can be used to reconstruct the parameters of the fireball and its environment and provide constraints on particle acceleration and magnetic field amplification in relativistic blast waves.",

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author = "Jonathan Granot and Abraham Loeb",

note = "Funding Information: This work was supported in part by the Horowitz foundation and the US-Israel BSF grant BSF-9800225 (for J. G.) and by NASA grants NAG5-7039 and NAG5-7768, NSF grants AST 99-00877 and AST 00-71019, and US-Israel BSF grant BSF-9800343 (for A. L.).",

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AU - Loeb, Abraham

N1 - Funding Information: This work was supported in part by the Horowitz foundation and the US-Israel BSF grant BSF-9800225 (for J. G.) and by NASA grants NAG5-7039 and NAG5-7768, NSF grants AST 99-00877 and AST 00-71019, and US-Israel BSF grant BSF-9800343 (for A. L.).

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N2 - We calculate the radial surface brightness profile of the image of a gamma-ray burst (GRB) afterglow. The afterglow spectrum consists of several power-law segments separated by breaks. The image profile changes considerably across each of the spectral breaks. It also depends on the density profile of the ambient medium into which the GRB fireball propagates. Gravitational microlensing by an intervening star can resolve the afterglow image. We calculate the predicted magnification history of GRB afterglows as a function of observed frequency and ambient medium properties. We find that intensive monitoring of a microlensed afterglow light curve can be used to reconstruct the parameters of the fireball and its environment and provide constraints on particle acceleration and magnetic field amplification in relativistic blast waves.

AB - We calculate the radial surface brightness profile of the image of a gamma-ray burst (GRB) afterglow. The afterglow spectrum consists of several power-law segments separated by breaks. The image profile changes considerably across each of the spectral breaks. It also depends on the density profile of the ambient medium into which the GRB fireball propagates. Gravitational microlensing by an intervening star can resolve the afterglow image. We calculate the predicted magnification history of GRB afterglows as a function of observed frequency and ambient medium properties. We find that intensive monitoring of a microlensed afterglow light curve can be used to reconstruct the parameters of the fireball and its environment and provide constraints on particle acceleration and magnetic field amplification in relativistic blast waves.

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KW - Gravitational lensing

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Chromatic signatures in the microlensing of gamma-ray burst afterglows

Abstract

Bibliographical note

Keywords

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