JCMT observations of Soft Gamma-Ray Repeaters

The spectra of the quiescent counterparts to the Soft Gamma-Ray Repeaters SGR 1900+14 and SGR 1806–20 peak in the infrared. Their infrared spectra appear to contain several components: the photospheric emission from star(s) dominates at shorter wavelengths, a bright point source dominates at 25 μm, while an extended source dominates at 60 μm. However, we show here that these counterparts were not detected by the James Clerk Maxwell Telescope at 450 μm or 800 μm. These observations are consistent with other millimeter studies, and are consistent with the detection of a point-like “core” to the radio nebula of SGR 1806–20. We show that monoenergetic synchrotron radiation and black body spectra are too broad to be consistent with both the infrared and submillimeter observations. However, simple dust models can explain the combined observations.