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Analysis of GeV-band gamma-ray emission from supernova remnant RX J1713.7-3946

  • Context. RX J1713.7-3946 is the brightest shell-type supernova remnant (SNR) of the TeV gamma-ray sky. Earlier Fermi-LAT results on low energy gamma-ray emission suggested that, despite large uncertainties in the background determination, the spectrum is inconsistent with a hadronic origin. Aims. We update the GeV-band spectra using improved estimates for the diffuse Galactic gamma-ray emission and more than double the volume of data. We further investigate the viability of hadronic emission models for RX J1713.7-3946. Methods. We produced a high-resolution map of the diffuse Galactic gamma-ray background corrected for the HI self-absorption and used it in the analysis of more than five years worth of Fermi-LAT data. We used hydrodynamic scaling relations and a kinetic transport equation to calculate the acceleration and propagation of cosmic rays in SNR. We then determined spectra of hadronic gamma-ray emission from RX J1713.7-3946, separately for the SNR interior and the cosmic-ray precursor region of the forward shock, andContext. RX J1713.7-3946 is the brightest shell-type supernova remnant (SNR) of the TeV gamma-ray sky. Earlier Fermi-LAT results on low energy gamma-ray emission suggested that, despite large uncertainties in the background determination, the spectrum is inconsistent with a hadronic origin. Aims. We update the GeV-band spectra using improved estimates for the diffuse Galactic gamma-ray emission and more than double the volume of data. We further investigate the viability of hadronic emission models for RX J1713.7-3946. Methods. We produced a high-resolution map of the diffuse Galactic gamma-ray background corrected for the HI self-absorption and used it in the analysis of more than five years worth of Fermi-LAT data. We used hydrodynamic scaling relations and a kinetic transport equation to calculate the acceleration and propagation of cosmic rays in SNR. We then determined spectra of hadronic gamma-ray emission from RX J1713.7-3946, separately for the SNR interior and the cosmic-ray precursor region of the forward shock, and computed flux variations that would allow us to test the model with observations. Results. We find that RX J1713.7-3946 is now detected by Fermi-LAT with very high statistical significance, and the source morphology is best described by that seen in the TeV band. The measured spectrum of RX J1713.7-3946 is hard with index gamma = 1.53 +/- 0.07, and the integral flux above 500 MeV is F = (5 : 5 +/- 1 : 1) x 10(-9) photons cm(-2) s(-1). We demonstrate that scenarios based on hadronic emission from the cosmic-ray precursor region are acceptable for RX J1713.7-3946, and we predict a secular flux increase at a few hundred GeV at the level of around 15% over ten years, which may be detectable with the upcoming Cherenkov Telescope Array (CTA) observatory.show moreshow less

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Metadaten
Author:Simone FedericiGND, Martin PohlORCiDGND, Igor Telezhinsky, Alina Wilhelm, Vikram V. Dwarkadas
DOI:https://doi.org/10.1051/0004-6361/201424947
ISSN:0004-6361 (print)
ISSN:1432-0746 (online)
Parent Title (English):Astronomy and astrophysics : an international weekly journal
Publisher:EDP Sciences
Place of publication:Les Ulis
Document Type:Article
Language:English
Year of first Publication:2015
Year of Completion:2015
Release Date:2017/03/27
Tag:ISM: supernova remnants; astroparticle physics; cosmic rays; gamma rays: ISM
Volume:577
Pagenumber:9
Funder:Helmholtz Alliance for Astroparticle Physics HAP - Initiative and Networking Fund of the Helmholtz Association; NASA Fermi grant [NNX12A057G]
Organizational units:Mathematisch-Naturwissenschaftliche Fakultät / Institut für Physik und Astronomie
Peer Review:Referiert