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Title: FERMI LARGE AREA TELESCOPE OBSERVATIONS OF THE SUPERNOVA REMNANT G8.7-0.1

Abstract

We present a detailed analysis of the GeV gamma-ray emission toward the supernova remnant (SNR) G8.7-0.1 with the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope. An investigation of the relationship between G8.7-0.1 and the TeV unidentified source HESS J1804-216 provides us with an important clue on diffusion process of cosmic rays if particle acceleration operates in the SNR. The GeV gamma-ray emission is extended with most of the emission in positional coincidence with the SNR G8.7-0.1 and a lesser part located outside the western boundary of G8.7-0.1. The region of the gamma-ray emission overlaps spatially connected molecular clouds, implying a physical connection for the gamma-ray structure. The total gamma-ray spectrum measured with LAT from 200 MeV-100 GeV can be described by a broken power-law function with a break of 2.4 {+-} 0.6 (stat) {+-} 1.2 (sys) GeV, and photon indices of 2.10 {+-} 0.06 (stat) {+-} 0.10 (sys) below the break and 2.70 {+-} 0.12 (stat) {+-} 0.14 (sys) above the break. Given the spatial association among the gamma rays, the radio emission of G8.7-0.1, and the molecular clouds, the decay of {pi}{sup 0}s produced by particles accelerated in the SNR and hitting the molecular cloudsmore » naturally explains the GeV gamma-ray spectrum. We also find that the GeV morphology is not well represented by the TeV emission from HESS J1804-216 and that the spectrum in the GeV band is not consistent with the extrapolation of the TeV gamma-ray spectrum. The spectral index of the TeV emission is consistent with the particle spectral index predicted by a theory that assumes energy-dependent diffusion of particles accelerated in an SNR. We discuss the possibility that the TeV spectrum originates from the interaction of particles accelerated in G8.7-0.1 with molecular clouds, and we constrain the diffusion coefficient of the particles.« less

Authors:
; ; ; ; ; ; ; ;  [1]; ; ;  [2];  [3];  [4]; ;  [5];  [6];  [7];  [8];
  1. W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States)
  2. Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa (Italy)
  3. Laboratoire AIM, CEA-IRFU/CNRS/Universite Paris Diderot, Service d'Astrophysique, CEA Saclay, 91191 Gif sur Yvette (France)
  4. Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, I-34127 Trieste (Italy)
  5. Istituto Nazionale di Fisica Nucleare, Sezione di Padova, I-35131 Padova (Italy)
  6. Istituto Nazionale di Fisica Nucleare, Sezione di Perugia, I-06123 Perugia (Italy)
  7. Dipartimento di Fisica 'M. Merlin' dell'Universita e del Politecnico di Bari, I-70126 Bari (Italy)
  8. Laboratoire Leprince-Ringuet, Ecole polytechnique, CNRS/IN2P3, Palaiseau (France)
Publication Date:
OSTI Identifier:
22004318
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 744; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCELERATION; ASTROPHYSICS; COSMIC RADIATION; ENERGY DEPENDENCE; GAMMA RADIATION; GAMMA SPECTRA; MORPHOLOGY; SUPERNOVA REMNANTS; TELESCOPES; TEV RANGE

Citation Formats

Ajello, M, Allafort, A, Bechtol, K, Berenji, B, Blandford, R D, Bloom, E D, Borgland, A W, Buehler, R, Cameron, R A, Baldini, L, Bellazzini, R, Bregeon, J, Ballet, J, Barbiellini, G, Bastieri, D, Buson, S, Bonamente, E, Brigida, M, Bruel, P, Caliandro, G. A., E-mail: hanabata@hep01.hepl.hiroshima-u.ac.jp, E-mail: katagiri@mx.ibaraki.ac.jp, and others, and. FERMI LARGE AREA TELESCOPE OBSERVATIONS OF THE SUPERNOVA REMNANT G8.7-0.1. United States: N. p., 2012. Web. doi:10.1088/0004-637X/744/1/80.
Ajello, M, Allafort, A, Bechtol, K, Berenji, B, Blandford, R D, Bloom, E D, Borgland, A W, Buehler, R, Cameron, R A, Baldini, L, Bellazzini, R, Bregeon, J, Ballet, J, Barbiellini, G, Bastieri, D, Buson, S, Bonamente, E, Brigida, M, Bruel, P, Caliandro, G. A., E-mail: hanabata@hep01.hepl.hiroshima-u.ac.jp, E-mail: katagiri@mx.ibaraki.ac.jp, & others, and. FERMI LARGE AREA TELESCOPE OBSERVATIONS OF THE SUPERNOVA REMNANT G8.7-0.1. United States. https://doi.org/10.1088/0004-637X/744/1/80
Ajello, M, Allafort, A, Bechtol, K, Berenji, B, Blandford, R D, Bloom, E D, Borgland, A W, Buehler, R, Cameron, R A, Baldini, L, Bellazzini, R, Bregeon, J, Ballet, J, Barbiellini, G, Bastieri, D, Buson, S, Bonamente, E, Brigida, M, Bruel, P, Caliandro, G. A., E-mail: hanabata@hep01.hepl.hiroshima-u.ac.jp, E-mail: katagiri@mx.ibaraki.ac.jp, and others, and. 2012. "FERMI LARGE AREA TELESCOPE OBSERVATIONS OF THE SUPERNOVA REMNANT G8.7-0.1". United States. https://doi.org/10.1088/0004-637X/744/1/80.
@article{osti_22004318,
title = {FERMI LARGE AREA TELESCOPE OBSERVATIONS OF THE SUPERNOVA REMNANT G8.7-0.1},
author = {Ajello, M and Allafort, A and Bechtol, K and Berenji, B and Blandford, R D and Bloom, E D and Borgland, A W and Buehler, R and Cameron, R A and Baldini, L and Bellazzini, R and Bregeon, J and Ballet, J and Barbiellini, G and Bastieri, D and Buson, S and Bonamente, E and Brigida, M and Bruel, P and Caliandro, G. A., E-mail: hanabata@hep01.hepl.hiroshima-u.ac.jp, E-mail: katagiri@mx.ibaraki.ac.jp and others, and},
abstractNote = {We present a detailed analysis of the GeV gamma-ray emission toward the supernova remnant (SNR) G8.7-0.1 with the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope. An investigation of the relationship between G8.7-0.1 and the TeV unidentified source HESS J1804-216 provides us with an important clue on diffusion process of cosmic rays if particle acceleration operates in the SNR. The GeV gamma-ray emission is extended with most of the emission in positional coincidence with the SNR G8.7-0.1 and a lesser part located outside the western boundary of G8.7-0.1. The region of the gamma-ray emission overlaps spatially connected molecular clouds, implying a physical connection for the gamma-ray structure. The total gamma-ray spectrum measured with LAT from 200 MeV-100 GeV can be described by a broken power-law function with a break of 2.4 {+-} 0.6 (stat) {+-} 1.2 (sys) GeV, and photon indices of 2.10 {+-} 0.06 (stat) {+-} 0.10 (sys) below the break and 2.70 {+-} 0.12 (stat) {+-} 0.14 (sys) above the break. Given the spatial association among the gamma rays, the radio emission of G8.7-0.1, and the molecular clouds, the decay of {pi}{sup 0}s produced by particles accelerated in the SNR and hitting the molecular clouds naturally explains the GeV gamma-ray spectrum. We also find that the GeV morphology is not well represented by the TeV emission from HESS J1804-216 and that the spectrum in the GeV band is not consistent with the extrapolation of the TeV gamma-ray spectrum. The spectral index of the TeV emission is consistent with the particle spectral index predicted by a theory that assumes energy-dependent diffusion of particles accelerated in an SNR. We discuss the possibility that the TeV spectrum originates from the interaction of particles accelerated in G8.7-0.1 with molecular clouds, and we constrain the diffusion coefficient of the particles.},
doi = {10.1088/0004-637X/744/1/80},
url = {https://www.osti.gov/biblio/22004318}, journal = {Astrophysical Journal},
issn = {0004-637X},
number = 1,
volume = 744,
place = {United States},
year = {Sun Jan 01 00:00:00 EST 2012},
month = {Sun Jan 01 00:00:00 EST 2012}
}