THE COSMOLOGICAL EVOLUTION OF COMPACT RADIO-SOURCES FROM 102-MHZ OBSERVATIONS

A survey of compact (theta < 1 '') radio sources was conducted at 102 MHz on the Large Phased Array of the Lebedev Institute of Physics usin g interplanetary scintillation observations. The survey covers a 0.097 -ster area of the 7C survey in the direction alpha = 10(h)28(m) and de lta = 41 degrees. A total of 289 scintillating radio sources were dete cted. A survey of two areas of the 7C survey enabled the detection of 395 compact radio sources, 380 for the first time. The scintillating s ource counts for these two areas confirm the sharp decrease of the den sity of compact radio sources at weak flux densities indicated by obse rvations of the first area alone. To roughly S = 0.6 Jy, the different ial scintillating source counts differ little from the source counts e xpected for a Euclidean Universe, however, a drop-off in the source co unt curve is observed for S < 0.6 Jy. This dropoff is significantly st eeper than that for counts of extended sources from the 7C survey. Thi s supports our earlier conclusion that compact and extended sources ex hibit different cosmological evolution.