Studying the SGR 1806-20/Cl* 1806-20 Region Using the Fermi Large Area Telescope
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 γ-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 Fermi Large Area Telescope (LAT), we identified an extended LAT source to the southwest 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}{{b}}=297+/- 15 {MeV}. The index above E b is 2.60 ± 0.04 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 January 21-March 7) is also reported. We discuss possible origins of the extended LAT source in the context of both leptonic and hadronic scenarios.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- August 2016
- DOI:
- 10.3847/0004-637X/827/1/41
- arXiv:
- arXiv:1606.01707
- Bibcode:
- 2016ApJ...827...41Y
- Keywords:
-
- cosmic rays;
- ISM: individual objects: SNR G9.7-0.0;
- HESS J1808-204;
- W31;
- pulsars: individual: SGR 1806-20;
- stars: magnetars;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- Accepted for publication in ApJ