The population of M dwarfs observed at low radio frequencies

TL;DR

This study reveals that coherent low-frequency radio emission is common among M dwarfs, regardless of their activity levels, suggesting magnetospheric processes similar to planets may be responsible, with implications for star-planet interactions.

Contribution

First blind low-frequency survey detecting M dwarf radio emission, demonstrating its ubiquity and independence from activity indicators, and proposing planetary magnetosphere analogues as emission sources.

Findings

19 M dwarf radio detections in a flux-limited survey

Radio emission is widespread across the M dwarf main sequence

Emission origin varies, with some linked to chromospheric activity, others not.

Abstract

Coherent low-frequency ($\lesssim 200$ MHz) radio emission from stars encodes the conditions of the outer corona, mass-ejection events, and space weather. Previous low-frequency searches for radio emitting stellar systems have lacked the sensitivity to detect the general population, instead largely focusing on targeted studies of anomalously active stars. Here we present 19 detections of coherent radio emission associated with known M~dwarfs from a blind flux-limited low-frequency survey. Our detections show that coherent radio emission is ubiquitous across the M~dwarf main sequence, and that the radio luminosity is independent of known coronal and chromospheric activity indicators. While plasma emission can generate the low-frequency emission from the most chromospherically active stars of our sample, the origin of the radio emission from the most quiescent sources is yet to be ascertained. Large-scale analogues of the magnetospheric processes seen in gas-giant planets likely drive the radio emission associated with these quiescent stars. The slowest-rotating stars of this sample are candidate systems to search for star-planet interaction signatures.