Huub Rottgering
Universiteit Leiden
Netherlands
“Opening up the Low Frequency Radio Sky to Study the Extragalactic Universe”
Abstract
At very low frequencies, the new pan-European radio telescope, LOFAR, is opening the last unexplored window of the electromagnetic spectrum for astrophysical studies. Operating at frequencies from 15 to 240 MHz, its superb sensitivity, high angular resolution, large field of view and flexible spectroscopic capabilities represent a dramatic improvement over previous facilities at these wavelengths. LOFAR is carrying out a broad range of fundamental astrophysical studies in a number of key science topics including the formation and evolution of clusters, galaxies and black holes.
In this contribution we will describe some of the capabilities of LOFAR and how they enable the planned LOFAR low-frequency radio sky surveys. However, producing wide-field radio maps with LOFAR at low frequencies is not easy. This is due to issues such as the need to deal with varying station beams, ionospheric corruption, radio frequency interference and staggering data-rates. The main challenge can be summarized as that the radio equivalent of an multi-conjugate adaptive optics system needs to be built to correct for the ionosphere. In the last part of the talk we will present LOFAR results, emphasizing those that are relevant for studying the formation and evolution of galaxy clusters and proto-clusters. Galaxy clusters are unique laboratories to study some of the most fundamental questions in astrophysics, related to the formation and evolution of galaxies, the physics of particle acceleration, the generation of magnetic fields, the growth of large-scale structure, and cosmology.