Abramowski, A.de Wilt, P.Dickinson, H.Maxted, N.Mayer, M.Rowell, G.2014-05-142014-05-142014Astronomy and Astrophysics: a European journal, 2014; 562(February 2014):1-100004-63611432-0746http://hdl.handle.net/2440/82892Extent: 10 p.Composite supernova remnants (SNRs) constitute a small subclass of the remnants of massive stellar explosions where non-thermal radiation is observed from both the expanding shell-like shock front and from a pulsar wind nebula (PWN) located inside of the SNR. These systems represent a unique evolutionary phase of SNRs where observations in the radio, X-ray, and γ-ray regimes allow the study of the co-evolution of both these energetic phenomena. In this article, we report results from observations of the shell-type SNR G 15.4+0.1 performed with the High Energy Stereoscopic System (H.E.S.S.) and XMM-Newton. A compact TeV γ-ray source, HESS J1818−154, located in the center and contained within the shell of G 15.4+0.1 is detected by H.E.S.S. and featurs a spectrum best represented by a power-law model with a spectral index of −2.3 ± 0.3stat ± 0.2sys and an integral flux of F(> 0.42 TeV) = (0.9 ± 0.3stat ± 0.2sys) × 10-12 cm-2 s-1. Furthermore, a recent observation with XMM-Newton reveals extended X-ray emission strongly peaked in the center of G 15.4+0.1. The X-ray source shows indications of an energy-dependent morphology featuring a compact core at energies above 4 keV and more extended emission that fills the entire region within the SNR at lower energies. Together, the X-ray and VHE γ-ray emission provide strong evidence of a PWN located inside the shell of G 15.4+0.1 and this SNR can therefore be classified as a composite based on these observations. The radio, X-ray, and γ-ray emission from the PWN is compatible with a one-zone leptonic model that requires a low average magnetic field inside the emission region. An unambiguous counterpart to the putative pulsar, which is thought to power the PWN, has been detected neither in radio nor in X-ray observations of G 15.4+0.1.en© ESO, 2014X-rays: individuals: G15.4+0.1gamma rays: generalmethods: observationalsupernovae: individual: HESS J1818-154X-rays: generalJournal article00300000742014051410352710.1051/0004-6361/2013229140003321618001332-s2.0-8489384870464080Rowell, G. [0000-0002-9516-1581]