Detection of radio emission from a nova-like cataclysmic variable: evidence of jets?

Abstract

ABSTRACT Jets have been detected in many accreting compact objects, and recently indications for jets have finally been found for transient cataclysmic variables (dwarf novae). However, so far, there have been no convincing reports of radio emission from white dwarfs undergoing stable disc accretion at a high rate, the so-called nova-like variables. Here, we present the first reproducible radio detection of a nova-like cataclysmic variable. The accretion rate and the distance of the detected source V3885 Sgr are comparable to the dwarf nova SS Cyg during its plateau phase. The detected radio emission is also of a similar level, although the source seems to show a steep spectrum. Besides V3885 Sgr, we have also observed IX Vel as well as reanalysed the available data for AC Cnc. Due to dynamic range limitations for IX Vel, we were not able to reach the required sensitivity and only obtained an upper limit. For AC Cnc we cannot confirm the previous detection. We discuss the detection of V3885 Sgr in the context of other types of accreting objects and conclude that the most likely source of the radio emission is optically thin synchrotron emission originating in a jet. Thus, tentative evidence for jets has now been found in both steady and transient CVs, making a universal connection between disc accretion and jet formation possible.