EVN e-VLBI observations of galactic transients

Abstract

e-VLBI (electronic very long baseline interferometry) is a new implementation of the VLBI technique consisting in transferring the data from the radio telescopes to the correlator over the internet and correlating them in real time. Time-wise this is a major improvement over the traditional method. e-VLBI is thus offering new opportunitie for radio transient studies. Its capability of rapid response enables a more efficient decision making process with respect to potential follow-up observations. The rapid feedback time also permits to quickly modify the observing strategy to best track the development of the transient phenomena. The results summarized here have been obtained with the EVN (European VLBI Network) in the past few years within a transient ToO programme. The targets were XRBs (X-ray binaries) undergoing periods of enhanced activity (outbursts). The EVN observations were performed at 5 GHz and were often complemented by simultaneous (within one day) data at other wavelengths (X-ray and optical). The findings reveal a complex behaviour of the accretion/ejection phenomena in the systems investigated and offer insights into the extreme physics close to a compact object.