HESS J1818-154, a new composite supernova remnant discovered in TeV gamma rays and X-rays
Klochkov, D.; Santangelo, A.; Quirrenbach, A.; Carrigan, S.; Conrad, J.; Farnier, C.; Giavitto, G.; Grondin, M. -H.; Lemoine-Goumard, M.; Reimer, A.; Reimer, O.; Venter, C.; Schlickeiser, R.; Petrucci, P. -O.; Colafrancesco, S.; Giebels, B.; Stawarz, Ł.; Fontaine, G.; Daniel, M. K.; Hervet, O.; Boisson, C.; Aharonian, F.; Akhperjanian, A. G.; Bernlöhr, K.; 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.; Khélifi, B.; Komin, Nu.; Lemière, A.; 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.; 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.; Böttcher, M.; Meyer, M.; Lamanna, G.; Bissaldi, E.; Chaves, R. C. G.; Mayer, M.; Schulz, A.; Renaud, M.; Cerruti, M.; de Oña Wilhelmi, E.; Anton, G.; Becherini, Y.; Bolmont, J.; Brucker, J.; Brun, F.; Brun, P.; Bulik, T.; Cheesebrough, A.; Dalton, M.; Davids, I. D.; Deil, C.; Dickinson, H. J.; Domainko, W.; Dyks, J.; Dyrda, M.; Egberts, K.; Eger, P.; Fegan, S.; Fiasson, A.; Förster, A.; Füßling, M.; Hofverberg, P.; Jacholkowska, A.; Jahn, C.; Jung, I.; Katarzyński, K.; Katz, U.; Kaufmann, S.; Kluźniak, W.; Kneiske, T.; Kosack, K.; Lenain, J. -P.; Marandon, V.; Méhault, J.; Moderski, R.; Moulin, E.; 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.; Stinzing, F.; Szostek, A.; van Eldik, C.; Volpe, F.; Zdziarski, A. A.; Zech, A.; H. E. S. S. Collaboration; Abramowski, A.; Ait Benkhali, F.; Balenderan, S.; Balzer, A.; Barnacka, A.; Becker Tjus, J.; Birsin, E.; Biteau, J.; Bordas, P.; Casanova, S.; Chalme-Calvet, R.; Chrétien, M.; Cologna, G.; Couturier, C.; Cui, Y.; deWilt, P.; Dutson, K.; Edwards, T.; Fernandes, M. V.; Fernandez, D.; Gajdus, M.; Garrigoux, T.; Grudzińska, M.; Häffner, S.; Hahn, J.; Harris, J.; Hillert, A.; Holler, M.; Jamrozy, M.; Janiak, M.; Jankowsky, F.; Kastendieck, M. A.; Kieffer, M.; Klepser, S.; Kolitzus, D.; Krakau, S.; Krayzel, F.; Krüger, P. P.; Laffon, H.; Lefaucheur, J.; Lopatin, A.; Lu, C. -C.; Marx, R.; Maurin, G.; Maxted, N.; Meintjes, P. J.; Menzler, U.; Mohamed, M.; Murach, T.; Oakes, L.; Opitz, B.; Oya, I.; Parsons, R. D.; Pekeur, N. W.; Peyaud, B.; Poon, H.; Raab, S.; de los Reyes, R.; Romoli, C.; Sanchez, D. A.; Schüssler, F.; Spengler, G.; Spies, F.; Stycz, K.; Tavernier, T.; Taylor, A. M.; Trichard, C.; Valerius, K.; van Soelen, B.; Viana, A.; Vorster, M.; Vuillaume, T.; Wagner, P.; Weidinger, M.; Weitzel, Q.; White, R.; Wierzcholska, A.; Willmann, P.; Wörnlein, A.; Wouters, D.; Zabalza, V.; Zacharias, M.; Zechlin, H. -S.; Lennarz, D.; Naumann, C. L.; Zajczyk, A.; Drury, L. O'C.; Perez, J.; Angüner, E.
Germany, Ireland, Armenia, United Kingdom, Poland, Sweden, Austria, France, South Africa, United States, Namibia, Australia, Czech Republic
Abstract
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.