Modelling Oscillations in the Jet Emission from Microquasar GRS 1915+105

Abstract

The variability in the infrared to millimetre emission from microquasar GRS 1915+105 is believed to be dominated by the system's relativistic jet. In this paper we develop a time-dependent version of the Blandford & Koenigl (1979) jet emission model and apply it to the oscillations in the infrared and millimetre emission from GRS 1915+105 observed by Fender & Pooley (2000). The resulting model provides a reasonable description of the observed flux oscillations from GRS 1915+105. From a fit of the observed time lag between the flux peaks in the infrared and millimetre emission together with the flux normalisation we were able to determine the model parameters for the GRS 1915+105 jet. We find that to achieve the observed flux levels with the model requires an unphysically large electron density within the jet. We therefore conclude that the Blandford & Koenigl (1979) model cannot explain these observations, either because it does not provide the correct description of the emission from microquasar jets, or because the observed emission variations do not originate in the jet.