The growth, polarization, and motion of the radio afterglow from the giant flare from SGR 1806-20

G. B. Taylor, Joseph (Yosi) Gelfand, B. M. Gaensler, J. Granot, C. Kouveliotou, R. P. Fender, E. Ramirez-Ruiz, D. Eichler, Y. E. Lyubarsky, M. Garrett, R. A.M.J. Wijers

    Research output: Contribution to journalArticle

    Abstract

    The extraordinary giant flare (GF) of 2004 December 27 from the soft gamma repeater SGR 1806-20 was followed by a bright radio afterglow. We present an analysis of VLA observations of this radio afterglow from SGR 1806-20, consisting of previously reported 8.5 GHz data covering days 7-20 after the GF, plus new observations at 8.5 and 22 GHz from day 24 to 81. We detect motion in the flux centroid of the afterglow, at an average velocity of (0.26 ± 0.03)c (assuming a distance of 15 kpc) at a position angle of -45°. This motion, in combination with the growth and polarization measurements, suggests an asymmetric outflow, mainly from one side of the magnetar. We find a deceleration in the expansion, from ∼9 to <5 mas day-1. The time of deceleration is roughly coincident with the rebrightening in the radio light curve, as expected to result when the ejecta from the GF sweeps up enough of the external medium and transitions from a coasting phase to the Sedov-Taylor regime. The radio afterglow is elongated and maintains a 2 : 1 axis ratio with an average position angle of -40° (north through east), oriented perpendicular to the average intrinsic linear polarization angle.

    Original languageEnglish (US)
    JournalAstrophysical Journal
    Volume634
    Issue number1 II
    DOIs
    StatePublished - Nov 20 2005

    Fingerprint

    afterglows
    flares
    polarization
    radio
    deceleration
    soft gamma repeaters
    magnetars
    ejecta
    linear polarization
    centroids
    light curve
    coverings
    outflow
    expansion

    Keywords

    • Pulsars: individual (SGR 1806-20)
    • Radio continuum: general
    • Stars: flare
    • Stars: neutron
    • Stars: winds, outflows

    ASJC Scopus subject areas

    • Astronomy and Astrophysics
    • Space and Planetary Science

    Cite this

    Taylor, G. B., Gelfand, J. Y., Gaensler, B. M., Granot, J., Kouveliotou, C., Fender, R. P., ... Wijers, R. A. M. J. (2005). The growth, polarization, and motion of the radio afterglow from the giant flare from SGR 1806-20. Astrophysical Journal, 634(1 II). https://doi.org/10.1086/491648

    The growth, polarization, and motion of the radio afterglow from the giant flare from SGR 1806-20. / Taylor, G. B.; Gelfand, Joseph (Yosi); Gaensler, B. M.; Granot, J.; Kouveliotou, C.; Fender, R. P.; Ramirez-Ruiz, E.; Eichler, D.; Lyubarsky, Y. E.; Garrett, M.; Wijers, R. A.M.J.

    In: Astrophysical Journal, Vol. 634, No. 1 II, 20.11.2005.

    Research output: Contribution to journalArticle

    Taylor, GB, Gelfand, JY, Gaensler, BM, Granot, J, Kouveliotou, C, Fender, RP, Ramirez-Ruiz, E, Eichler, D, Lyubarsky, YE, Garrett, M & Wijers, RAMJ 2005, 'The growth, polarization, and motion of the radio afterglow from the giant flare from SGR 1806-20', Astrophysical Journal, vol. 634, no. 1 II. https://doi.org/10.1086/491648
    Taylor GB, Gelfand JY, Gaensler BM, Granot J, Kouveliotou C, Fender RP et al. The growth, polarization, and motion of the radio afterglow from the giant flare from SGR 1806-20. Astrophysical Journal. 2005 Nov 20;634(1 II). https://doi.org/10.1086/491648
    Taylor, G. B. ; Gelfand, Joseph (Yosi) ; Gaensler, B. M. ; Granot, J. ; Kouveliotou, C. ; Fender, R. P. ; Ramirez-Ruiz, E. ; Eichler, D. ; Lyubarsky, Y. E. ; Garrett, M. ; Wijers, R. A.M.J. / The growth, polarization, and motion of the radio afterglow from the giant flare from SGR 1806-20. In: Astrophysical Journal. 2005 ; Vol. 634, No. 1 II.
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    AU - Granot, J.

    AU - Kouveliotou, C.

    AU - Fender, R. P.

    AU - Ramirez-Ruiz, E.

    AU - Eichler, D.

    AU - Lyubarsky, Y. E.

    AU - Garrett, M.

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