Discovery of the two “wings” of the Kookaburra complex in VHE γ-rays with HESS

Aharonian, F; Akhperjanian, AG; Bazer-Bachi, AR; Beilicke, M; Benbow, W; Berge, D; Bernlohr, K; Boisson, C; Bolz, O; Borrel, V; Braun, I; Brown, AM; Buhler, R; Busching, I; Carrigan, S; Chadwick, PM; Chounet, LM; Cornils, R; Costamante, L; Degrange, B; Dickinson, HJ; Djannati-Atai, A; Drury, LOC; Dubus, G; Egberts, K; Emmanoulopoulos, D; Espigat, P; Feinstein, F; Ferrero, E; Fiasson, A; Fontaine, G; Funk, S; Fussling, M; Gallant, YA; Giebels, B; Glicenstein, JF; Goret, P; Hadjichristidis, C; Hauser, D; Hauser, M; Heinzelmann, G; Henri, G; Hermann, G; Hinton, JA; Hoffmann, A; Hofmann, W; Holleran, M; Horns, D; Jacholkowska, A; de Jager, OC; Kendziorra, E; Khelifi, B; Komin, N; Konopelko, A; Kosack, K; Latham, IJ; Le Gallou, R; Lemiere, A; Lemoine-Goumard, M; Lohse, T; Martin, JM; Martineau-Huynh, O; Marcowith, A; Masterson, C; Maurin, G; McComb, TJL; de Naurois, M; Nedbal, D; Nolan, SJ; Noutsos, A; Orford, KJ; Osborne, JL; Ouchrif, M; Panter, M; Pelletier, G; Pita, S; Pulhofer, G; Punch...

Abstract

Aims.Search for Very High Energy $\gamma$-ray emission in the Kookaburra complex through observations with the HESS array. Methods.Stereoscopic imaging of Cherenkov light emission of the $\gamma$-ray showers in the atmosphere is used for the reconstruction and selection of the events to search for $\gamma$-ray signals. Their spectrum is derived by a forward-folding maximum likelihood fit. Results.Two extended $\gamma$-ray sources with an angular (68%) radius of 3.3-3.4´ are discovered at high (>13$\sigma$) statistical significance: HESS J1420-607 and HESS J1418-609. They exhibit a flux above 1 TeV of ( $2.97 \pm 0.18_{\rm stat} \pm 0.60_{\rm sys}) \times 10^{-12}$ and ( $2.17 \pm 0.17_{\rm stat} \pm 0.43_{\rm sys}) \times 10^{-12}$ cm-2 s-1, respectively, and similar hard photon indices ~2.2. Multi-wavelength comparisons show spatial coincidence with the wings of the Kookaburra. Two pulsar wind nebulæ candidates, K3/PSR J1420-6048 and the Rabbit, lie on the edge of the HESS sources. Conclusions. The two new sources confirm the non-thermal nature of at least parts of the two radio wings which overlap with the $\gamma$-ray emission and establish their connection with the two X-ray pulsar wind nebulæ candidates. Given the large point spread function of EGRET, the unidentified source(s) 3EG J1420-6038/GeV J1417-6100 could possibly be related to either or both HESS sources. The most likely explanation for the Very High Energy $\gamma$-rays discovered by HESS is inverse Compton emission of accelerated electrons on the Cosmic Microwave Background near the two candidate pulsar wind nebulæ, K3/PSR J1420-6048 and the Rabbit. Two scenarios which could lead to the observed large (~10 pc) offset-nebula type morphologies are briefly discussed.

Citation

Aharonian, F., Akhperjanian, A., Bazer-Bachi, A., Beilicke, M., Benbow, W., Berge, D., …Ward, M. (2006). Discovery of the two “wings” of the Kookaburra complex in VHE γ-rays with HESS. Astronomy & Astrophysics, 456(1), 245-251. https://doi.org/10.1051/0004-6361%3A20065511

• Journal Article Type: Article
• Publication Date: 2006-09
• Journal: Astronomy and astrophysics.
• Print ISSN: 0004-6361
• Electronic ISSN: 1432-0746
• Publisher: EDP Sciences
• Peer Reviewed: Peer Reviewed
• Volume: 456
• Issue: 1
• Pages: 245-251
• DOI: https://doi.org/10.1051/0004-6361%3A20065511
• Keywords: ISM : general; gamma rays : observations; radiation mechanisms :non-thermal2ND EGRET CATALOG; SUPERNOVA-REMNANTS; BOW-SHOCK; GEV J1417-6100;PULSAR; NEBULAE; SIMULATIONS; SYSTEM