NICER and Fermi GBM Observations of the First Galactic Ultraluminous X-Ray Pulsar Swift J0243.6+6124

Research output: Contribution to journalJournal article – Annual report year: 2018Researchpeer-review

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DOI

  • Author: Wilson-Hodge, Colleen A

    NASA Marshall Space Flight Center, United States

  • Author: Malacaria, Christian

    NASA Marshall Space Flight Center, United States

  • Author: Jenke, Peter A.

    University of Alabama in Huntsville, United States

  • Author: Jaisawal, Gaurava Kumar

    Astrophysics and Atmospheric Physics, National Space Institute, Technical University of Denmark, Elektrovej, 2800, Kgs. Lyngby, Denmark

  • Author: Kerr, Matthew

    U.S. Naval Research Laboratory , United States

  • Author: Wolff, Michael T.

    U.S. Naval Research Laboratory , United States

  • Author: Arzoumanian, Zaven

    NASA Goddard Space Flight Center, United States

  • Author: Chakrabarty, Deepto

    Massachusetts Institute of Technology, United States

  • Author: Doty, John P.

    Noqsi Aerospace Ltd., United States

  • Author: Gendreau, Keith C.

    NASA Goddard Space Flight Center, United States

  • Author: Guillot, Sebastien

    CNRS, France

  • Author: Ho, Wynn C. G.

    University of Southampton, United Kingdom

  • Author: LaMarr, Beverly

    Massachusetts Institute of Technology, United States

  • Author: Markwardt, Craig B.

    NASA Goddard Space Flight Center, United States

  • Author: Özel, Feryal

    University of Arizona, United States

  • Author: Prigozhin, Gregory Y.

    Massachusetts Institute of Technology, United States

  • Author: Ray, Paul S.

    U.S. Naval Research Laboratory , United States

  • Author: Ramos-Lerate, Mercedes

    European Space Astronomy Centre and European Space Agency, Spain

  • Author: Remillard, Ronald A.

    Massachusetts Institute of Technology, United States

  • Author: Strohmayer, Tod E.

    NASA Goddard Space Flight Center, United States

  • Author: Vezie, Michael L.

    Massachusetts Institute of Technology, United States

  • Author: Wood, Kent S.

    Praxis, Inc., United States

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Swift J0243.6+6124 is a newly discovered Galactic Be/X-ray binary, revealed in late 2017 September in a giant outburst with a peak luminosity of 2 × 1039(d/7 kpc)2 erg s−1 (0.1–10 keV), with no formerly reported activity. At this luminosity, Swift J0243.6+6124 is the first known galactic ultraluminous X-ray pulsar. We describe Neutron star Interior Composition Explorer (NICER) and Fermi Gamma-ray Burst Monitor (GBM) timing and spectral analyses for this source. A new orbital ephemeris is obtained for the binary system using spin frequencies measured with GBM and 15–50 keV fluxes measured with the Neil Gehrels Swift Observatory Burst Alert Telescope to model the system's intrinsic spin-up. Power spectra measured with NICER show considerable evolution with luminosity, including a quasi-periodic oscillation near 50 mHz that is omnipresent at low luminosity and has an evolving central frequency. Pulse profiles measured over the combined 0.2–100 keV range show complex evolution that is both luminosity and energy dependent. Near the critical luminosity of L ~ 1038 erg s−1, the pulse profiles transition from single peaked to double peaked, the pulsed fraction reaches a minimum in all energy bands, and the hardness ratios in both NICER and GBM show a turnover to softening as the intensity increases. This behavior repeats as the outburst rises and fades, indicating two distinct accretion regimes. These two regimes are suggestive of the accretion structure on the neutron star surface transitioning from a Coulomb collisional stopping mechanism at lower luminosities to a radiation-dominated stopping mechanism at higher luminosities. This is the highest observed (to date) value of the critical luminosity, suggesting a magnetic field of B ~ 1013 G
Original languageEnglish
Article number1
JournalAstrophysical Journal Supplement Series
Volume863
Issue number1
Number of pages20
ISSN0067-0049
DOIs
Publication statusPublished - 2018
CitationsWeb of Science® Times Cited: No match on DOI

    Research areas

  • Accretion, Accretion disks , Pulsars: individual (SWIFT J0243.6+6124), X-rays: binaries

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ID: 151911273