The Nature of a Homogeneous Sample of Compact Radio Sources Variable at 151 MHz

Abstract

AbstractGlobal VLBI snapshot observations at 1.6 GHz (5 EVN + 4 VLBA) of a sample of low-frequency variable (LFV) radio sources found using the Cambridge Low Frequency Synthesis Telescope (CLFST) are presented. Variability at 151 MHz is almost certainly due to propagation effects in our Galaxy (e.g., refractive interstellar scintillation). Theory indicates that only sources with a significant fraction of their low-frequency flux coming from components with angular sizes ≲ 30 mas will show such effects. This is confirmed by the VLBI images.