Implications of burst oscillations from the slowly rotating accreting pulsar IGR J17480-2446 in the globular cluster Terzan 5

Y Cavecchi, A Patruno, B Haskell, A L Watts, Yuri Levin, M Linares, D Altamirano, R Wijnands, Michiel Van der Klis

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    Abstract

    The recently discovered accreting X-ray pulsar IGR J17480-2446 spins at a frequency of a??11Hz. We show that Type I X-ray bursts from this source display oscillations at the same frequency as the stellar spin. IGR J17480-2446 is the first secure case of a slowly rotating neutron star (NS) which shows Type I burst oscillations (BOs), all other sources featuring such oscillations spin at hundreds of Hertz. This means that we can test BO models in a completely different regime. We explore the origin of Type I BOs in IGR J17480-2446 and conclude that they are not caused by global modes in the NS ocean. We also show that the Coriolis force is not able to confine an oscillation-producing hot spot on the stellar surface. The most likely scenario is that the BOs are produced by a hot spot confined by hydromagnetic stresses.
    Original languageEnglish
    Pages (from-to)1 - 5
    Number of pages5
    JournalThe Astrophysical Journal Letters
    Volume740
    Issue number1
    DOIs
    Publication statusPublished - 2011

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