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arXiv · 1102.1548

Implications of burst oscillations from the slowly rotating accreting pulsar IGR 17480-2446 in the globular cluster Terzan 5

Y. Cavecchi·A. Patruno·B. Haskell·A. L. Watts·Y. Levin·M. Linares·D. Altamirano·R. Wijnands·M. van der Klis
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Abstract

The recently-discovered accreting X-ray pulsar IGR J17480--2446 spins at a frequency of ~11 Hz. 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 which shows Type I burst oscillations, all other sources featuring such oscillations spin at hundreds of Hertz. This means that we can test burst oscillation models in a completely different regime. We explore the origin of Type I burst oscillations in IGR J17480--2446 and conclude that they are not caused by global modes in the neutron star 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 burst oscillations are produced by a hot-spot confined by hydromagnetic stresses.

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Y. Cavecchi, A. Patruno, B. Haskell, A. L. Watts, Y. Levin, M. Linares, D. Altamirano, R. Wijnands, M. van der Klis. 2011-02-08. Implications of burst oscillations from the slowly rotating accreting pulsar IGR 17480-2446 in the globular cluster Terzan 5. https://doi.org/10.1088/2041-8205/740/1/l8

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