Title:
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Hard X-Ray emission from Sh 2-104: a NuSTAR search for Gamma-Ray counterparts
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Author:
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Gotthelf, E. V.; Mori, K.; Aliu, E.; Paredes i Poy, Josep Maria; Tomsick, J. A.; Boggs, S. E.; Christensen, F. E.; Craig, W. W.; Hailey, C. J.; Harrison, F. A.; Hong, J. S.; Rahoui, F.; Stern, D.; Zhang, W. W.
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Other authors:
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Universitat de Barcelona |
Abstract:
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We present NuSTAR hard X-ray observations of Sh 2-104, a compact H ii region containing several young massive stellar clusters (YMSCs). We have detected distinct hard X-ray sources coincident with localized VERITAS TeV emission recently resolved from the giant gamma-ray complex MGRO J2019+37 in the Cygnus region. Fainter, diffuse X-rays coincident with the eastern YMSC in Sh2-104 likely result from the colliding winds of a component star. Just outside the radio shell of Sh 2-104 lies 3XMM J201744.7+365045 and a nearby nebula, NuSTAR J201744.3+364812, whose properties are most consistent with extragalactic objects. The combined XMM-Newton and NuSTAR spectrum of 3XMM J201744.7+365045 is well-fit to an absorbed power-law model with ${N}_{{\rm{H}}}=(3.1\pm 1.0)\times {10}^{22}$ cm−2 and a photon index ${\rm{\Gamma }}=2.1\pm 0.1$. Based on possible long-term flux variation and the lack of detected pulsations (≤43% modulation), this object is likely a background active galactic nucleus rather than a Galactic pulsar. The spectrum of the NuSTAR nebula shows evidence of an emission line at E = 5.6 keV, suggesting an optically obscured galaxy cluster at z = 0.19 ± 0.02 (d = 800 Mpc) and L X = 1.2 × 1044 erg s−1. Follow-up Chandra observations of Sh 2-104 will help identify the nature of the X-ray sources and their relation to MGRO J2019+37. We also show that the putative VERITAS excess south of Sh 2-104, is most likely associated with the newly discovered Fermi pulsar PSR J2017+3625 and not the H ii region. |
Subject(s):
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-Astronomia de raigs X -Raigs gamma -Estels de neutrons -X-ray astronomy -Gamma rays -Neutron stars |
Rights:
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(c) American Astronomical Society, 2016
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Document type:
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Article Article - Published version |
Published by:
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Institute of Physics (IOP)
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