Timing and spectral properties of the accreting millisecond pulsar SWIFT J1756.9-2508

Abstract

SWIFT J1756.9-2508 is one of the few accreting millisecond pulsars (AMPs) discovered to date. We report here the results of our analysis of its aperiodic X-ray variability, as measured with the Rossi X-ray Timing Explorer during the 2007 outburst of the source. We detect strong (~35%) flat-topped broadband noise throughout the outburst with low characteristic frequencies (~0.1 Hz). This makes SWIFT J1756.9-2508 similar to the rest of AMPs and to other low luminosity accreting neutron stars when they are in their hard states, and enables us to classify this AMP as an atoll source in the extreme island state. We also find a hard tail in its energy spectrum extending up to 100 keV, fully consistent with such source and state classification.

arXiv commentAccepted for publication in The Astrophysical Journal. Scheduled for the ApJ May 10, 2008, v678n 2 issue. 6 pages, 5 figures. Uses \emulateapj

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• Discovery of a new accreting millisecond X-ray pulsar in the globular cluster NGC 2808
• Discovery of an accreting millisecond pulsar in the eclipsing binary system Swift J1749.4-2807
• Indications of non-conservative mass-transfer in AMXPs
• SWIFT J1756.9-2508: spectral and timing properties of its 2018 outburst
• The aperiodic X-ray variability of the accreting millisecond pulsar SAX J1808.4-3658
• Swift J1734.5-3027: a new long type-I X-ray bursting source
• Testing jet geometries and disk-jet coupling in the neutron star LMXB 4U 0614+091 with the internal shocks model
• Possible twin kHz Quasi Periodic Oscillations in the accreting millisecond X-ray Pulsar IGR J17511-3057
• Outbursts from IGR J17473-2721
• Broad-band X-ray spectra and timing of the accretion-powered millisecond pulsar Swift J1756.9$-$2508 during its 2018 and 2019 outbursts