NuSTAR detection of a cyclotron line in the supergiant fast X-ray transient IGR J17544-2619

Varun Bhalerao, Patrizia Romano, John Tomsick, Lorenzo Natalucci, David M. Smith, Eric Bellm, Steven E. Boggs, Deepto Chakrabarty, Finn Erland Christensen, William W. Craig, Felix Fuerst

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    We present NuSTAR spectral and timing studies of the supergiant fast X-ray transient (SFXT) IGR J17544-2619. The spectrum is well described by an  ∼ 1 keV blackbody and a hard continuum component, as expected from an accreting X-ray pulsar. We detect a cyclotron line at 17 keV, confirming that the compact object in IGR J17544-2619 is indeed a neutron star. This is the first measurement of the magnetic field in an SFXT. The inferred magnetic field strength, B = (1.45 +/- 0.03) x 1012 G (1 + z) is typical of neutron stars in X-ray binaries, and rules out a magnetar nature for the compact object. We do not find any significant pulsations in the source on time-scales of 1-2000 s.
    Original languageEnglish
    JournalMonthly Notices of the Royal Astronomical Society
    Issue number3
    Pages (from-to)2274-2281
    Publication statusPublished - 2015


    • X-rays: binaries
    • X-rays: individual: IGR J17544-2619


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