ﻻ يوجد ملخص باللغة العربية
We present 610-MHz Giant Metrewave Radio Telescope observations of 0.84 deg$^2$ of the AMI001 field (centred on $00^{rm h} 23^{rm m} 10^{rm s}$, $+31^{circ} 53$) with an r.m.s. noise of 18 $mu$Jy beam$^{-1}$ in the centre of the field. 955 sources are detected, and 814 are included in the source count analysis. The source counts from these observations are consistent with previous work. We have used these data to study the spectral index distribution of a sample of sources selected at 15.7 GHz from the recent deep extension to the Tenth Cambridge (10C) survey. The median spectral index, $alpha$, (where $S propto u^{-alpha}$) between $0.08 < S_{15.7~rm GHz} / rm mJy < 0.2$ is $0.32 pm 0.14$, showing that star-forming galaxies, which have much steeper spectra, are not contributing significantly to this population. This is in contrast to several models, but in agreement with the results from the 10C ultra-deep source counts; the high-frequency sky therefore continues to be dominated by radio galaxies down to $S_{15.7~rm GHz} = 0.1$ mJy.
Studies have shown that mergers of massive galaxy clusters produce shocks and turbulence in the intra-cluster medium, the possible event that creates radio relics, as well as the radio halos. Here we present GMRT dual-band (235 and 610~MHz) radio obs
We study the space density evolution of active galactic nuclei (AGN) using the $610 mathrm{MHz}$ radio survey of the XXL-North field, performed with the Giant Metrewave Radio Telescope (GMRT). The survey covers an area of $30.4 mathrm{deg}^2$, with
Planck data has not found the smoking gun of non-Gaussianity that would have necessitated consideration of inflationary models beyond the simplest canonical single field scenarios. This raises the important question of what these results do imply for
Ultra-deep radio surveys are an invaluable probe of dust-obscured star formation, but require a clear understanding of the relative contribution from radio AGN to be used to their fullest potential. We study the composition of the $mu$Jy radio popula
We study the faint radio population using wide-field very long baseline interferometry (VLBI) observations of 2865 known radio sources in the Cosmic Evolution Survey (COSMOS) field. The main objective of the project was to determine where active gala