Gamma-ray burst afterglow scaling relations for the full blast wave evolution

Hendrik J. Van Eerten, Andrew I. MacFadyen

    Research output: Contribution to journalArticlepeer-review


    We demonstrate that gamma-ray burst afterglow spectra and light curves can be calculated for arbitrary explosion and radiation parameters by scaling the peak flux and the critical frequencies connecting different spectral regimes. Only one baseline calculation needs to be done for each jet opening angle and observer angle. These calculations are done numerically using high-resolution relativistic hydrodynamical afterglow blast wave simulations which include the two-dimensional dynamical features of expanding and decelerating afterglow blast waves. Any light curve can then be generated by applying scaling relations to the baseline calculations. As a result, it is now possible to fully fit for the shape of the jet break, e.g., at early-time X-ray and optical frequencies. In addition, late-time radio calorimetry can be improved since the general shape of the transition into the Sedov-Taylor regime is now known for arbitrary explosion parameters so the exact moment when the Sedov-Taylor asymptote is reached in the light curve is no longer relevant. When calculating the baselines, we find that the synchrotron critical frequency νm and the cooling break frequency νc are strongly affected by the jet break. The νm temporal slope quickly drops to the steep late-time Sedov-Taylor slope, while the cooling break νc first steepens and then rises to meet the level of its shallow late-time asymptote.

    Original languageEnglish (US)
    Article numberL30
    JournalAstrophysical Journal Letters
    Issue number2
    StatePublished - Mar 10 2012


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

    ASJC Scopus subject areas

    • Astronomy and Astrophysics
    • Space and Planetary Science


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