Discovery of VHE emission towards the Carina arm region with the H.E.S.S. telescope array: HESS J1018-589
Klochkov, D.; Santangelo, A.; Quirrenbach, A.; Ripken, J.; Carrigan, S.; Conrad, J.; Reimer, A.; Reimer, O.; Venter, C.; Schlickeiser, R.; Petrucci, P. -O.; Giebels, B.; Stawarz, Ł.; Fontaine, G.; Daniel, M. K.; Hauser, M.; Boisson, C.; Aharonian, F.; Akhperjanian, A. G.; Chadwick, P. M.; Degrange, B.; Djannati-Ataï, A.; Dubus, G.; Espigat, P.; Feinstein, F.; Gallant, Y. A.; Glicenstein, J. F.; Heinzelmann, G.; Henri, G.; Hermann, G.; Hinton, J. A.; Hofmann, W.; Horns, D.; de Jager, O. C.; Khélifi, B.; Komin, Nu.; Lohse, T.; Marcowith, A.; McComb, T. J. L.; de Naurois, M.; Nolan, S. J.; Panter, M.; Pelletier, G.; Pita, S.; Pühlhofer, G.; Punch, M.; Raue, M.; Rayner, S. M.; Rob, L.; Rowell, G.; Sahakian, V.; Schwanke, U.; Sol, H.; Steenkamp, R.; Stegmann, C.; Tavernet, J. -P.; Terrier, R.; Tluczykont, M.; Vasileiadis, G.; Vincent, P.; Völk, H. J.; Wagner, S. J.; Ward, M.; Heinz, S.; Kossakowski, R.; Lamanna, G.; Acero, F.; Chaves, R. C. G.; Mayer, M.; Schulz, A.; Renaud, M.; Cerruti, M.; de Oña Wilhelmi, E.; Anton, G.; Becherini, Y.; Bochow, A.; Bolmont, J.; Brucker, J.; Brun, F.; Brun, P.; Bulik, T.; Büsching, I.; Charbonnier, A.; Cheesebrough, A.; Dalton, M.; Davids, I. D.; Deil, C.; Dickinson, H. J.; Domainko, W.; Dyks, J.; Dyrda, M.; Egberts, K.; Eger, P.; Fallon, L.; Fegan, S.; Fiasson, A.; Förster, A.; Füßling, M.; Gérard, L.; Gerbig, D.; Glück, B.; Göring, D.; Hofverberg, P.; Jacholkowska, A.; Jahn, C.; Jung, I.; Katarzyński, K.; Katz, U.; Kaufmann, S.; Keogh, D.; Kneiske, T.; Kosack, K.; Lenain, J. -P.; Marandon, V.; Masbou, J.; Medina, M. C.; Méhault, J.; Moderski, R.; Moulin, E.; Naumann-Godo, M.; Nedbal, D.; Nekrassov, D.; Nicholas, B.; Niemiec, J.; Ohm, S.; Ostrowski, M.; Paz Arribas, M.; Rieger, F.; Rosier-Lees, S.; Rudak, B.; Rulten, C. B.; Schwarzburg, S.; Schwemmer, S.; Sushch, I.; Skilton, J. L.; Stinzing, F.; Szostek, A.; van Eldik, C.; Volpe, F.; Vorobiov, S.; Zdziarski, A. A.; Zech, A.; H. E. S. S. Collaboration; Abramowski, A.; Balzer, A.; Barnacka, A.; Birsin, E.; Biteau, J.; Bordas, P.; Casanova, S.; Cologna, G.; Dutson, K.; Fernandes, M. V.; Häffner, S.; Hahn, J.; Harris, J.; Hillert, A.; Holler, M.; Jamrozy, M.; Kastendieck, M. A.; Krayzel, F.; Laffon, H.; Lopatin, A.; Lu, C. -C.; Maxted, N.; Mohamed, M.; Opitz, B.; Oya, I.; Pekeur, N. W.; Peyaud, B.; de los Reyes, R.; Sanchez, D. A.; Spengler, G.; Stycz, K.; Valerius, K.; Viana, A.; Vorster, M.; White, R.; Wierzcholska, A.; Zacharias, M.; Zechlin, H. -S.; Becker, J.; Gast, H.; Hague, J. D.; Hampf, D.; Lennarz, D.; Naumann, C. L.; Nguyen, N.; Zajczyk, A.; Drury, L. O'C.; Perez, J.; Sheidaei, F.; Bernlöh, K.; Klużniak, D.
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.