Project Part A10: LOFAR total-intensity surveys of nearby galaxies

Persons involved


In this new project the low-frequency radio emission from nearby galaxies will be investigated. It is based on radio continuum surveys of the northern sky with the new LOFAR radio telescope. These so-called 'Tier 1' surveys, which will commence towards the end of 2013, are using the 'highband array' (HBA) in the frequency range 120 - 180 MHz and the 'lowband array' (LBA) to cover 15 - 65 MHz. The large number of observed galaxies will facilitate statistical analyses, two of which form the body of this project. The first sub-project is the cross-correlation of these surveys with other galaxy catalogues, to build up a comprehensive compilation of galaxy flux densities, radio spectra and other properties, to test hypotheses of emission and absorption mechanisms and of the radio-far-infrared correlation. The second sub-project is concerned with the spatial variations of radio spectra from a sample of galaxies with high spatial resolution, using the HBA survey. The goals are to measure cosmic-ray cooling times, scale lengths of the radio disks and other properties. Furthermore, a search for diffuse polarised radiation and for polarised background sources will be conducted, using Faraday rotation measure synthesis. Methods towards an optimised imaging will be developed in close collaboration with Project A9 (self-calibration loops etc.). The technique of three-dimensional 'Faraday Synthesis', developed in the framework of Project A8, will be applied. Finally, this project will come up with a selection of galaxies for deeper observations, to be conducted in the framework of the 'Tier 2' survey.