NuSTAR Hard X-Ray Observation of the Gamma-Ray Binary Candidate HESS J1832–093

Kaya Mori, E. V. Gotthelf, Charles J. Hailey, Ben J. Hord, Emma de Oña Wilhelmi, Farid Rahoui, John A. Tomsick, Shuo Zhang, Jaesub Hong, Amani M. Garvin, Steven E. Boggs, Finn Erland Christensen, William W. Craig, Fiona A. Harrison, Daniel Stern, William W. Zhang

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    We present a hard X-ray observation of the TeV gamma-ray binary candidate HESS J1832−093, which is coincident with the supernova remnant G22.7−0.2, using the Nuclear Spectroscopic Telescope Array. Non-thermal X-ray emission from XMMU J183245−0921539, the X-ray source associated with HESS J1832−093, is detected up to ~30 keV and is well-described by an absorbed power-law model with a best-fit photon index . A re-analysis of archival Chandra and XMM-Newton data finds that the long-term X-ray flux increase of XMMU J183245−0921539 is (90% C.L.), much less than previously reported. A search for a pulsar spin period or binary orbit modulation yields no significant signal to a pulse fraction limit of in the range 4 ms  ks. No red noise is detected in the FFT power spectrum to suggest active accretion from a binary system. While further evidence is required, we argue that the X-ray and gamma-ray properties of XMMU J183245−0921539 are most consistent with a non-accreting binary generating synchrotron X-rays from particle acceleration in the shock formed as a result of the pulsar and stellar wind collision. We also report on three nearby hard X-ray sources, one of which may be associated with diffuse emission from a fast-moving supernova fragment interacting with a dense molecular cloud.
    Original languageEnglish
    Article number80
    JournalAstrophysical Journal
    Issue number2
    Number of pages8
    Publication statusPublished - 2017


    • Gamma rays: general
    • Radiation mechanisms: non-thermal
    • X-rays: binaries


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