No flares from gamma-ray burst afterglow blast waves encountering sudden circumburst density change

Ilana Gat, Hendrik Van Eerten, Andrew Macfadyen

    Research output: Contribution to journalArticle

    Abstract

    Afterglows of gamma-ray bursts are observed to produce light curves with the flux following power-law evolution in time. However, recent observations reveal bright flares at times on the order of minutes to days. One proposed explanation for these flares is the interaction of a relativistic blast wave with a circumburst density transition. In this paper, we model this type of interaction computationally in one and two dimensions, using a relativistic hydrodynamics code with adaptive mesh refinement called RAM, and analytically in one dimension. We simulate a blast wave traveling in a stellar wind environment that encounters a sudden change in density, followed by a homogeneous medium, and compute the observed radiation using a synchrotron model. We show that flares are not observable for an encounter with a sudden density increase, such as a wind termination shock, nor for an encounter with a sudden density decrease. Furthermore, by extending our analysis to two dimensions, we are able to resolve the spreading, collimation, and edge effects of the blast wave as it encounters the change in circumburst medium. In all cases considered in this paper, we find that a flare will not be observed for any of the density changes studied.

    Original languageEnglish (US)
    Article number2
    JournalAstrophysical Journal
    Volume773
    Issue number1
    DOIs
    StatePublished - Aug 10 2013

    Fingerprint

    blasts
    afterglows
    gamma ray bursts
    flares
    encounters
    homogeneous medium
    edge effect
    stellar winds
    collimation
    traveling waves
    light curve
    synchrotrons
    power law
    hydrodynamics
    shock
    interactions
    radiation

    Keywords

    • gamma-ray burst: general
    • hydrodynamics
    • methods: numerical
    • shock waves

    ASJC Scopus subject areas

    • Space and Planetary Science
    • Astronomy and Astrophysics

    Cite this

    No flares from gamma-ray burst afterglow blast waves encountering sudden circumburst density change. / Gat, Ilana; Van Eerten, Hendrik; Macfadyen, Andrew.

    In: Astrophysical Journal, Vol. 773, No. 1, 2, 10.08.2013.

    Research output: Contribution to journalArticle

    Gat, Ilana ; Van Eerten, Hendrik ; Macfadyen, Andrew. / No flares from gamma-ray burst afterglow blast waves encountering sudden circumburst density change. In: Astrophysical Journal. 2013 ; Vol. 773, No. 1.
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