Radio Morphologies and Spectra of Compact Radio Sources with the Steepest Spectra

Abstract

We have assembled a complete sample of 74 compact (θ ≤ 25'') radio sources visible from the northern hemisphere with spectral indexes 1.5 ≤ α ≤ 3.2 (where Sν ∝ ν-α) and 365 MHz flux densities S ≥ 200 mJy. These sources were selected from two large-scale radio surveys: the 1.4 GHz NRAO VLA Sky Survey and the 365 MHz Texas survey, which together cover almost 80% of the sky (-35°30' ≤ δ ≤ 71°30'). We present here high-resolution images for the sources and spectra compiled from our data and other surveys. We attempt to classify these sources based on morphology and size determined by additional radio observations using the Very Large Array. We cannot definitively classify the majority of the sources based on these data, but statistical arguments suggest most are distant radio galaxies. A small number of previously unknown pulsars may also exist in our sample.