Deeper H.E.S.S. observations of Vela Junior (RX J0852.0-4622): Morphology studies and resolved spectroscopy

Aims: We study γ-ray emission from the shell-type supernova remnant (SNR) RX J0852.0-4622 to better characterize its spectral properties and its distribution over the SNR. Methods: The analysis of an extended High Energy Spectroscopic System (H.E.S.S.) data set at very high energies (E > 100 GeV) permits detailed studies, as well as spatially resolved spectroscopy, of the morphology and spectrum of the whole RX J0852.0-4622 region. The H.E.S.S. data are combined with archival data from other wavebands and interpreted in the framework of leptonic and hadronic models. The joint Fermi-LAT-H.E.S.S. spectrum allows the direct determination of the spectral characteristics of the parent particle population in leptonic and hadronic scenarios using only GeV-TeV data. Results: An updated analysis of the H.E.S.S. data shows that the spectrum of the entire SNR connects smoothly to the high-energy spectrum measured by Fermi-LAT. The increased data set makes it possible to demonstrate that the H.E.S.S. spectrum deviates significantly from a power law and is well described by both a curved power law and a power law with an exponential cutoff at an energy of E<SUB>cut</SUB> = (6.7 ± 1.2<SUB>stat</SUB> ± 1.2<SUB>syst</SUB>) TeV. The joint Fermi-LAT-H.E.S.S. spectrum allows the unambiguous identification of the spectral shape as a power law with an exponential cutoff. No significant evidence is found for a variation of the spectral parameters across the SNR, suggesting similar conditions of particle acceleration across the remnant. A simple modeling using one particle population to model the SNR emission demonstrates that both leptonic and hadronic emission scenarios remain plausible. It is also shown that at least a part of the shell emission is likely due to the presence of a pulsar wind nebula around PSR J0855-4644. A FITS image of the region of interest and two text files describing the H.E.S.S. spectrum of RX J0852.0-4622 are only available at the CDS via anonymous ftp to <A href=http://cdsarc.u-strasbg.fr>http://cdsarc.u-strasbg.fr</A> (<A href=http://cdsarc.u-strasbg.fr>http://130.79.128.5</A>) or via <A href=http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/612/A7>http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/612/A7</A>