Two populations are better than one: Short gamma-ray bursts from SGR giant flares and NS-NS mergers

R. Chapman, R. Priddey, N. Tanvir

    Research output: Chapter in Book/Report/Conference proceedingConference contribution

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    Abstract

    With a peak luminosity of ~ 1047 erg s-1 the December 27th 2004 giant flare from SGR1806-20 would have been
    visible by BATSE (the Burst and Transient Source Experiment) out to ≈50 Mpc. It is thus plausible that some fraction
    of the short duration Gamma-Ray Bursts (sGRBs) in the BATSE catalogue were due to extragalactic magnetar giant flares.
    According to the most widely accepted current models, the remaining BATSE sGRBs were most likely produced by compact
    object (neutron star-neutron star or neutron star-black hole) mergers with intrinsically higher luminosities [1]. Previously, by
    examining correlations on the sky between BATSE sGRBs and galaxies within 155 Mpc, we placed limits on the proportion of
    nearby sGRBs [3]. Here, we examine the redshift distribution of sGRBs produced by assuming both one and two populations
    of progenitor with separate Luminosity Functions (LFs). Using the local Galactic SGR giant flare rate and theoretical NS-NS
    merger rates evolved according to well-known Star Formation Rate parameterisations, we constrain the predicted distributions
    by BATSE sGRB overall number counts. We show that only a dual population consisting of both SGR giant flares and NS-NS
    mergers can reproduce the likely local distribution of sGRBs as well as the overall number counts. In addition, the best fit LF
    parameters of both sub-populations are in good agreement with observed luminosities.

    Original languageEnglish
    Title of host publication40 Years of Pulsars
    Subtitle of host publicationMillisecond Pulsars, Magnetars and More
    PublisherAmerican Institute of Physics (AIP)
    Pages304-306
    Publication statusPublished - 2007

    Publication series

    NameAIP Conference Proceedings
    PublisherAmerican Institute of Physics
    Volume983

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