A MeerKAT Survey of Nearby Novalike Cataclysmic Variables

TL;DR

This study presents new radio observations of nearby novalike cataclysmic variables, detecting radio emission from four systems, and explores their multi-wavelength properties and correlations with other system parameters.

Contribution

First radio detections of IM Eri and an expanded sample of non-magnetic CVs, analyzing their radio, X-ray, and optical properties and correlations.

Findings

Detected radio emission from IM Eri, RW Sex, V3885 Sgr, V603 Aql.

Radio luminosities follow an extension of the L_X ∝ L_R^0.7 relation.

No other significant correlations between radio emission and other system parameters.

Abstract

We present the results of MeerKAT radio observations of eleven nearby novalike cataclysmic variables. We have detected radio emission from IM Eri, RW Sex, V3885 Sgr and V603 Aql. While RW Sex, V3885 Sgr and V603 Aql had been previously detected, this is the first reported radio detection of IM Eri. Our observations have doubled the sample of non-magnetic CVs with sensitive radio data. We observe that at our radio detection limits, a specific optical luminosity $\gtrsim 2.2\times 10^{18}$ erg/s/Hz (corresponding to $M_V \lesssim 6.0$) is required to produce a radio detection. We also observe that the X-ray and radio luminosities of our detected novalikes are on an extension of the $L_{X} \propto L_{R}^{\sim 0.7}$ power law originally proposed for non-pulsating neutron star low-mass X-ray binaries. We find no other correlations between the radio emission and emission in other wavebands or any other system parameters for the existing sample of radio-detected non-magnetic CVs. We measure in-band (0.9-1.7 GHz) radio spectral indices that are consistent with reports from earlier work. Finally, we constructed broad spectral energy distributions for our sample from published multi-wavelength data, and use them to place constraints on the mass transfer rates of these systems.