A Re-Brightening of the Radio Nebula Associated with the 2004 December 27 Giant Flare from SGR 1806-20
On 2004 Dec. 27, a giant {gamma}-ray flare was detected from the magnetar SGR 1806-20. A radio observation seven days later revealed an expanding radio nebula at this position. Here we present results from an on-going monitoring campaign of this source with the Australia Telescope Compact Array and Very Large Array. These data indicate that there was an increase in the observed flux ?25 days after the initial {gamma}-ray flare that lasted for {approx}3-5 days. In this Letter, we argue that this rebrightening marks the end of the coasting phase of the blast wave and the transition to the Sedov-Taylor phase. Assuming a distance to SGR 1806-20 of 15 kpc, we infer from the properties of this rebrightening that the blast wave is baryonic material of mass M {approx}> 10{sup 24.5} g. In an accompanying paper (Granot et al. 2005), we show that this material was initially expanding with a velocity of about 0.4c; we therefore infer a kinetic energy E {approx}> 10{sup 44.5} ergs. If this mass was blown off the outer layers of the magnetar, it may have emitted a burst of ultra-high energy (E > 1 TeV) neutrinos far in excess of what might be expected from other astrophysical sources.
- Research Organization:
- SLAC National Accelerator Lab., Menlo Park, CA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- AC02-76SF00515
- OSTI ID:
- 839904
- Report Number(s):
- SLAC-PUB-11062; TRN: US0503461
- Country of Publication:
- United States
- Language:
- English
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