Title: Study of TeV shell supernova remnants at gamma-ray energies

Abstract

The breakthrough developments of Cherenkov telescopes in the past decade have led to angular resolution of 0.1° and an unprecedented sensitivity. This has allowed the current generation of Cherenkov telescopes (H.E.S.S., MAGIC, and VERITAS) to discover a population of supernova remnants (SNRs) radiating in very-high-energy (VHE; E > 100 GeV) γ-rays. A number of those VHE SNRs exhibit a shell-type morphology that is spatially coincident with the shock front of the SNR. The members of this VHE shell SNR club are RX J1713.7-3946, RX J0852.0-4622, RCW 86, SN 1006, and HESS J1731-347. The last two objects have been poorly studied in high-energy (HE; 0.1 < E < 100 GeV) γ-rays and need to be investigated in order to draw the overall picture of this class of SNRs and to constrain the characteristics of the underlying population of accelerated particles. Using 6 years of Fermi-LAT P7 reprocessed data, we studied the GeV counterpart of the SNRs HESS J1731-347 and SN 1006. The two SNRs are not detected in the data set, and given that there is no hint of detection, we do not expect any detection in coming years from the SNRs. However in both cases, we derived upper limits thatmore » significantly constrain the γ-ray emission mechanism and can rule out a standard hadronic scenario with a confidence level >5σ. In conclusion, with this Fermi analysis, we now have a complete view of the HE to VHE γ-ray emission of TeV shell SNRs. All five sources have a hard HE photon index (Γ < 1.8), which suggests a common scenario where the bulk of the emission is produced by accelerated electrons radiating from radio to VHE γ-rays through synchrotron and inverse Compton processes. In addition when correcting for the distance, all SNRs show a surprisingly similar γ-ray luminosity supporting the idea of a common emission mechanism. While the γ-ray emission is likely to be leptonic-dominated at the scale of the whole SNR, this does not rule out efficient hadron acceleration in those objects.« less

Authors:

Acero, F. ^[1]; Lemoine-Goumard, M. ^[2]; Renaud, M. ^[3]; Ballet, J. ^[1]; Hewitt, J. W. ^[4]; Rousseau, R. ^[2]; Tanaka, T. ^[5]

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+ Show Author Affiliations

1. Univ. Paris Diderot, Gif sur Yvette (France). Lab. AIM
2. Univ. of Bordeaux (France). Centre d'Etudes Nucleaires de Bordeaux-Gradignan
3. Univ. Montpellier II (France). Lab. Univers. et Particules de Monpellier
4. Univ. of Maryland Baltimore County (UMBC), Baltimore, MD (United States). Center for Space Sciences and Technology, Dept. of Physics; NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States). Center for Research and Exploration in Space Science and Technology (CRESST)
5. Kyoto Univ. (Japan). Graduate School of Science, Dept. of Physics

Publication Date:

Wed Aug 05 00:00:00 EDT 2015

Research Org.:

SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)

Sponsoring Org.:

USDOE

OSTI Identifier:

1354922

Grant/Contract Number:  

AC02-76SF00515

Resource Type:

Accepted Manuscript

Journal Name:

Astronomy and Astrophysics

Additional Journal Information:

Journal Volume: 580; Journal ID: ISSN 0004-6361

Publisher:

EDP Sciences

Country of Publication:

United States

Language:

English

Subject:

79 ASTRONOMY AND ASTROPHYSICS; Astroparticle physics; Gamma-rays; ISM; supernova remnants