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dc.contributor.authorAbramowski, A.
dc.contributor.authorBöttcher, M.
dc.contributor.authorDavids, I.D.
dc.contributor.authorIvascenko, A.
dc.contributor.authorKrüger, P.P.
dc.contributor.authorPekeur, N.W.
dc.contributor.authorSeyffert, A.S.
dc.contributor.authorSpanier, F.
dc.contributor.authorSushch, I.
dc.contributor.authorVan der Walt, D.J.
dc.contributor.authorVenter, C.
dc.contributor.authorH.E.S.S. Collaboration
dc.date.accessioned2016-08-30T10:52:14Z
dc.date.available2016-08-30T10:52:14Z
dc.date.issued2015
dc.identifier.citationAbramowski, A. et al. 2015. Discovery of variable VHE γ-ray emission from the binary system 1FGL J1018.6-5856. Astronomy & astrophysics, 577: Article no A131. [https://doi.org/10.1051/0004-6361/201525699]en_US
dc.identifier.issn0004-6361
dc.identifier.issn1432-0746 (Online)
dc.identifier.urihttp://hdl.handle.net/10394/18448
dc.identifier.urihttps://doi.org/10.1051/0004-6361/201525699
dc.identifier.urihttp://www.aanda.org/articles/aa/full_html/2015/05/aa25699-15/aa25699-15.html
dc.description.abstractRe-observations with the HESS telescope array of the very high-energy (VHE) source HESS J1018–589 A that is coincident with the Fermi-LAT γ-ray binary 1FGL J1018.6–5856 have resulted in a source detection significance of more than 9σ and the detection of variability (χ2/ν of 238.3/155) in the emitted γ-ray flux. This variability confirms the association of HESS J1018–589 A with the high-energy γ-ray binary detected by Fermi-LAT and also confirms the point-like source as a new VHE binary system. The spectrum of HESS J1018–589 A is best fit with a power-law function with photon index Γ = 2.20 ± 0.14stat ± 0.2sys. Emission is detected up to ~20 TeV. The mean differential flux level is (2.9 ± 0.4) × 10-13 TeV-1 cm-2 s-1 at 1 TeV, equivalent to ~1% of the flux from the Crab Nebula at the same energy. Variability is clearly detected in the night-by-night light curve. When folded on the orbital period of 16.58 days, the rebinned light curve peaks in phase with the observed X-ray and high-energy phaseograms. The fit of the HESS phaseogram to a constant flux provides evidence of periodicity at the level of Nσ> 3σ. The shape of the VHE phaseogram and measured spectrum suggest a low-inclination, low-eccentricity system with amodest impact from VHE γ-ray absorption due to pair production (τ ≲ 1 at 300 GeV)en_US
dc.language.isoenen_US
dc.publisherEDP Sciencesen_US
dc.subjectX-rays: binariesen_US
dc.subjectgamma rays: starsen_US
dc.subjectstars: individual: 1FGL J1018.6-5856en_US
dc.subjectradiation mechanisms: non-thermalen_US
dc.subjectacceleration of particlesen_US
dc.titleDiscovery of variable VHE γ-ray emission from the binary system 1FGL J1018.6-5856en_US
dc.typeArticleen_US
dc.contributor.researchID24420530 - Böttcher, Markus
dc.contributor.researchID13146629 - Davids, Isak Delberth
dc.contributor.researchID24790052 - Ivascenko, Alex
dc.contributor.researchID11749903 - Krüger, Petrus Paulus
dc.contributor.researchID22050574 - Pekeur, Nicolette Whilna
dc.contributor.researchID25161814 - Spanier, Felix Alexander
dc.contributor.researchID24922986 - Sushch, Iurii
dc.contributor.researchID10060499 - Van der Walt, Diederick Johannes
dc.contributor.researchID12006653 - Venter, Christo
dc.contributor.researchID20126999 - Seyffert, Albertus Stefanus


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