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Discovery of VHE emission towards the Carina arm region with the HESS telescope array: HESSJ1018-589
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2012 (English)In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 541, A5- p.Article in journal (Refereed) Published
Abstract [en]

The Carina arm region, containing the supernova remnant SNRG284.3-1.8, the high-energy (HE; E > 100 MeV) binary 1FGL J1018.6-5856 and the energetic pulsar PSRJ1016-5857 and its nebula, has been observed with the H. E. S. S. telescope array. The observational coverage of the region in very-high-energy (VHE; E > 0.1TeV) gamma-rays benefits from deep exposure (40 h) of the neighboring open cluster Westerlund 2. The observations have revealed a new extended region of VHE gamma-ray emission. The new VHE source HESS J1018-589 shows a bright, point-like emission region positionally coincident with SNRG284.3-1.8 and 1FGL J1018.6-5856 and a diffuse extension towards the direction of PSRJ1016-5857. A soft (Gamma = 2.7 +/- 0.5(stat)) photon index, with a differential flux at 1 TeV of N-0 = (4.2 +/- 1.1) x 10(-13) TeV-1 cm(-2) s(-1) is found for the point-like source, whereas the total emission region including the diffuse emission region is well fit by a power-law function with spectral index Gamma = 2.9 +/- 0.4(stat) and differential flux at 1 TeV of N-0 = (6.8 +/- 1.6) x 10(-1)3 TeV-1 cm(-2) s(-1). This H. E. S. S. detection motivated follow-up X-ray observations with the XMM-Newton satellite to investigate the origin of the VHE emission. The analysis of the XMM-Newton data resulted in the discovery of a bright, non-thermal point-like source (XMMU J101855.4-58564) with a photon index of Gamma = 1.65 +/- 0.08 in the center of SNRG284.3-1.8, and a thermal, extended emission region coincident with its bright northern filament. The characteristics of this thermal emission are used to estimate the plasma density in the region as n approximate to 0.5 cm(-3) (2.9 kpc/d)(2). The position of XMMUJ101855.4-58564 is compatible with the position reported by the Fermi-LAT collaboration for the binary system 1FGL J1018.6-5856 and the variable Swift XRT source identified with it. The new X-ray data are used alongside archival multi-wavelength data to investigate the relationship between the VHE gamma-ray emission from HESS J1018-589 and the various potential counterparts in the Carina arm region.

Place, publisher, year, edition, pages
2012. Vol. 541, A5- p.
Keyword [en]
gamma rays: stars, ISM: individual objects: SNRG284.3-1.8, ISM: individual objects: 1FGL J1018.6-5856, ISM: individual objects: PSRJ1016-5857
National Category
Astronomy, Astrophysics and Cosmology
URN: urn:nbn:se:su:diva-80082DOI: 10.1051/0004-6361/201218843ISI: 000304390900005OAI: diva2:555791


Available from: 2012-09-21 Created: 2012-09-12 Last updated: 2012-09-21Bibliographically approved

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Conrad, JanDickinson, HughRipken, Joachim
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Department of PhysicsThe Oskar Klein Centre for Cosmo Particle Physics (OKC)
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