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Type: Journal article
Title: Discovery of VHE emission towards the Carina arm region with the H.E.S.S. telescope array: HESS J1018-589
Author: H.E.S.S. Collaboration
Abramowski, A.
Acero, F.
Aharonian, F.
Akhperjanian, A.
Anton, G.
Balzer, A.
Barnacka, A.
Becherini, Y.
Bernlöhr, K.
Becker, J.
Birsin, E.
Biteau, J.
Bochow, A.
Boisson, C.
Bolmont, J.
Bordas, P.
Brucker, J.
Brun, F.
Brun, P.
et al.
Citation: Astronomy and Astrophysics, 2012; 541:A5-1-A5-9
Publisher: EDP Sciences
Issue Date: 2012
ISSN: 0004-6361
Statement of
H.E.S.S. Collaboration, A. Abramowski ... N. Maxted ... B. Nicholas ... G. Rowell ... et al.
Abstract: The Carina arm region, containing the supernova remnant SNR G284.3–1.8, the high-energy (HE; E > 100 MeV) binary 1FGL J1018.6–5856 and the energetic pulsar PSR J1016–5857 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 > 0.1 TeV) γ-rays benefits from deep exposure (40 h) of the neighboring open cluster Westerlund 2. The observations have revealed a new extended region of VHE γ-ray emission. The new VHE source HESS J1018–589 shows a bright, point-like emission region positionally coincident with SNR G284.3–1.8 and 1FGL J1018.6–5856 and a diffuse extension towards the direction of PSR J1016–5857. A soft (Γ = 2.7 ± 0.5stat) photon index, with a differential flux at 1 TeV of N0 = (4.2 ± 1.1) × 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 Γ = 2.9 ± 0.4stat and differential flux at 1 TeV of N₀ = (6.8 ± 1.6) × 10⁻¹³ 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 Γ = 1.65 ± 0.08 in the center of SNR G284.3–1.8, 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 ≈ 0.5 cm⁻³ (2.9 kpc/d)². The position of XMMU J101855.4–58564 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 γ-ray emission from HESS J1018–589 and the various potential counterparts in the Carina arm region.
Keywords: gamma rays: stars; ISM: individual objects: SNRG284.3-1.8; ISM: individual objects: 1FGL J1018.6-5856; ISM: individual objects: PSRJ1016-5857
Description: Extent: 9p.
Rights: © ESO 2012
RMID: 0020119363
DOI: 10.1051/0004-6361/201218843
Appears in Collections:IPAS publications

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