出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：We have been studying several elds at low radio frequencies, such as ELAIS-N1, GOODS-N/S and the AKARI deep eld, and making deep images at metre-wavelengths using the Giant Metrewave Radio Telescope (GMRT). In this paper we largely summarise the results of the observations of ELAIS-N1 at 325 MHz, and present new results on the ECDFS at 150 and 325 MHz. These elds have been studied extensively at different wave-bands using the most powerful groundbased and space telescopes. The ELAIS-N1 image with the GMRT has an rms noise of 40 mJy beam1 towards the phase centre, while for the ECDFS eld the rms noise values are 2.5 mJy beam1 and 75mJy beam1 at 150 and 325 MHz respectively. The ECDFS observations also show a attening of the source counts at 1 mJy at 325 MHz, consistent with the results reported earlier for the ELAIS-N1 eld. The sub-mJy sources show a larger scatter in their spectral indices which is possibly at least partly due to a population of both starburst galaxies and low-luminosity AGN. These deep observations with the GMRT have helped identify a signicant number of very steep-spectrum sources, which could be either relic sources or candidate high-redshift galaxies.
