RT Journal Article
T1 Morphological and spectral properties of the W51 region measured with the MAGIC telescopes
A1 Antoranz Canales, Pedro
A1 Barrio Uña, Juan Abel
A1 Contreras González, José Luis
A1 Fonseca González, María Victoria
A1 Miranda Pantoja, José Miguel
A1 Scapin, Valeria
AB The W51 complex hosts the supernova remnant W51C which is known to interact with the molecular clouds in the star forming region W51B. In addition, a possible pulsar wind nebula CXO J192318.5+140305 was found likely associated with the supernova remnant. Gamma-ray emission from this region was discovered by Fermi/LAT (between 0.2 and 50 GeV) and H. E. S. S. (>1 TeV). The spatial distribution of the events could not be used to pinpoint the location of the emission among the pulsar wind nebula, the supernova remnant shell and/or the molecular cloud. However, the modeling of the spectral energy distribution presented by the Fermi/LAT collaboration suggests a hadronic emission mechanism. The possibility that the gamma-ray emission from such an object is of hadronic origin can contribute to solvingthe long-standing problem of the contribution to galactic cosmic rays by supernova remnants. Aims. Our aim is to determine the morphology of the very-high-energy gamma-ray emission of W51 and measure its spectral properties. Methods. We performed observations of the W51 complex with the MAGIC telescopes for more than 50 h. The energy range accessible with MAGIC extends from 50 GeV to several TeV, allowing for the first spectral measurement at these energies. In addition, the good angular resolution in the medium (few hundred GeV) to high (above 1 TeV) energies allow us to perform morphological studies. We look for underlying structures by means of detailed morphological studies. Multi-wavelength data from this source have been sampled to model the emission with both leptonic and hadronic processes. Results. We detect an extended emission of very-high-energy gamma rays, with a significance of 11 standard deviations. We extend the spectrum from the highest Fermi/LAT energies to similar to 5 TeV and find that it follows a single power law with an index of 2.58 +/- 0.07(stat) +/- 0.22(syst). The main part of the emission coincides with the shocked cloud region, while we find a feature extending towards the pulsar wind nebula. The possible contribution of the pulsar wind nebula, assuming a point-like source, shows no dependence on energy and it is about 20% of the overall emission. The broad band spectral energy distribution can be explained with a hadronic model that implies proton acceleration above 100 TeV. This result, together with the morphology of the source, tentatively suggests that we observe ongoing acceleration of ions in the interaction zone between supernova remnant and cloud.
PB EDP Sciencies
SN 0004-6361
YR 2012
FD 2012-05
LK https://hdl.handle.net/20.500.14352/43801
UL https://hdl.handle.net/20.500.14352/43801
LA eng
NO © ESO. We would like to thank the anonymous referee as well as the Associate Editor M. Walmsley for fruitful comments and suggestions. We would like to thank the Instituto de Astrofisica de Canarias for the excellent working conditions at the Observatorio del Roque de los Muchachos in La Palma.
NO German BMBF
NO German MPG
NO Italian INFN
NO Swiss National Fund SNF
NO Spanish MICINN
NO Marie Curie program
NO Bulgarian NSF
NO Academy of Finland
NO YIP of the Helmholtz Gemeinschaft;
NO DFG Cluster of Excelle
NO DFG Collaborative Research Centers
NO Polish MNiSzW
NO National Science Foundation
NO MultiDark
DS Docta Complutense
RD 8 abr 2025