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Studying the SGR 1806-20/Cl* 1806-20 region using the \emph{Fermi} Large Area Telescope

Authors :
Yeung, Paul K. H.
Kong, Albert K. H.
Tam, P. H. Thomas
Lin, Lupin C. C.
Hui, C. Y.
Hu, Chin-Ping
Cheng, K. S.
Publication Year :
2016

Abstract

The region around SGR 1806-20 and its host stellar cluster Cl* 1806-20 is a potentially important site of particle acceleration. The soft $\gamma-$ray repeater and Cl* 1806-20, which also contains several very massive stars including a luminous blue variable hypergiant LBV 1806-20, are capable of depositing a large amount of energy to the surroundings. Using the data taken with the \emph{Fermi} Large Area Telescope (LAT), we identified an extended LAT source to the south-west of Cl* 1806-20. The centroid of the 1-50~GeV emission is consistent with that of HESS J1808-204 (until now unidentified). The LAT spectrum is best-fit by a broken power-law with the break energy $E_\mathrm{b}=297\pm15$ MeV. The index above $E_\mathrm{b}$ is $2.60\pm0.04$, and is consistent with the flux and spectral index above 100 GeV for HESS J1808-204, suggesting an association between the two sources. Meanwhile, the interacting supernova remnant SNR G9.7-0.0 is also a potential contributor to the LAT flux. A tentative flux enhancement at the MeV band during a 45-day interval (2011 Jan 21 - 2011 Mar 7) is also reported. We discuss possible origins of the extended LAT source in the context of both leptonic and hadronic scenarios.<br />Comment: Accepted for publication in ApJ

Details

Database :
arXiv
Publication Type :
Report
Accession number :
edsarx.1606.01707
Document Type :
Working Paper
Full Text :
https://doi.org/10.3847/0004-637X/827/1/41