Radio Emission from the Magnetar SGR 1806-20 Giant Flare

A defining characteristic of magnetars, neutron stars with extremely strong surface magnetic fields, are giant γ-ray flares which have been detected on three separate occasions from these objects. According to the magnetar model, these giant flares are generated by "quakes" on the surface of the neutron star. The detection of the third such giant flare, on 2004 December 27 from SGR 1806-20 - the most luminous of these events - provided an important opportunity to test this model. Analysis of a VLA observation of SGR 1806-20 discovered a bright, variable radio source at the position of this neutron star whose properties (flux density, radio spectrum, size, and position) we have been monitoring for approximately three years after this giant flare. In this talk, I will argue that these observations strongly suggest a significant amount of baryonic material was ablated off the surface of SGR 1806-20 during the initial γ-ray spike of this giant flare, and discuss the implications of this result for giant flares in the magnetar model.