A broadband search for coherent radio emission in cataclysmic variables

TL;DR

This study analyzes broadband radio observations of six cataclysmic variables, revealing diverse polarized emission likely due to electron-cyclotron maser or plasma radiation, indicating complex magnetic and plasma interactions.

Contribution

First detailed spectro-temporal analysis of 2-12 GHz radio emission in multiple cataclysmic variables, identifying coherent emission processes and their potential origins.

Findings

Detection of both broad- and narrow-band polarized radio emission.

Evidence supporting electron-cyclotron maser or plasma radiation as emission mechanisms.

Observation of rapid unpolarized emission changes in V2400 Oph.

Abstract

Radio observations of cataclysmic variables have revealed a variety of behavior. From some systems, we see bright unpolarized radio flares occurring during dwarf nova outbursts, consistent with synchrotron emission from jets. In others, we see highly polarized emission, restricted in frequency, superimposed on a flat-spectrum continuum, suggesting a coherent emission process. Here, we present spectro-temporal analysis of 2--4 GHz and 8--12 GHz VLA observations of 6 cataclysmic variables. Our results show both broad- and narrow-band, highly polarized, variable radio emission. We suggest that this emission is consistent with electron-cyclotron maser emission or plasma radiation. This could be from an isolated emission region in the case of the narrow-band emission, or a region with varying magnetic field strength or density in the case of the broad-band emission. In one target, V2400 Oph, we see largely unpolarized emission changing on minute timescales, that may coincide with interactions between the white dwarf's magnetosphere and diamagnetic blobs.