Multi-frequency VLA observations of a new sample of CSS/GPS radio sources

In this paper we present a new sample of 87 Compact Steep Spectrum radio so urces (CSS) with flux density greater than or equal to0.8 Jy at 0.4 GHz. Th is sample has been selected from the B3-VLA sample with the aid of new VLA observations at 4.9 and 8.5 GHz which allowed to clean an earlier selection based an VLA 1.5 GHz data. Redshifts. either spectroscopic or photometric, are known for 62% of the sources, About 75% of the sources are resolved or slightly resolved in the new observations. The range of measured linear si zes is from 20 h(-1) kpc (selection upper limit) down to approximate to0.5 h(-1) kpc, which corresponds to our resolution limit, Tile Largest Linear S ize (LLS) distribution is well represented by the power law dN/d(LLS) propo rtional to LLS-0.6, consistent with earlier results, The majority of the ra dio sources: smaller than 0.5 h(-1) kpc shows a marked spectral flattening at low frequencies. The four frequency spectra computed in the range 0.4-8. 5 GHz display a significant steepening at high Frequencies in the largest m ajority of cases. A considerable fraction of source components are polarize d with median values of their fractional polarization approximate to6% and approximate to4% at 8.5 and 4.9 GH respectivetly.