  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.
