* Astronomy

Using its first station of distributed radio antennas, the Low Frequency Array (LOFAR) radio telescope has successfully detected the pulsar PSR B0329+54. The measurement took 15 minutes on 14 June and used only six of the prototype high-band antennas recently installed in the eastern part of the Netherlands. The results demonstrate the technical performance of the antennas.
LOFAR will be the largest radio telescope ever built, using a new concept based on a vast array of simple omni-directional antennas. The idea is to digitise the signals before sending them to a central digital processor where software will combine them to create the effect of a large conventional antenna. When finished, it will consist of 15,000 small antennas, distributed to more than 77 stations in the north east of the Netherlands and nearby parts of Germany. The array will operate at the lowest frequencies that can be observed from Earth, at 10240 MHz. Plans exist for the extension of the array beyond its initial 100 km scale, by building stations further into Germany and also in the UK, France, Sweden, Poland and Italy.
One important area of research, in addition to more conventional astronomy, will be the detection of extensive air showers originating from high-energy cosmic rays, and perhaps even neutrinos. Researchers have known since the 1960s that these showers produce radio signals that are detectable for cosmic-ray energies above 10^17 eV. The radio emission comes from charged particles in the shower, mainly electrons and positrons, which are deflected in the Earth's magnetic field and produce coherent synchrotron radiation. Electronic devices in the 1960s were not sensitive enough for reliable measurements of the radio emission. However, researchers have now developed new observational techniques and radio receiver systems such as those that LOFAR employs. Through its observations, LOFAR should be able to study the longitudinal development of air showers and reconstruct the original directions of the incident cosmic rays.

Source 

Title: LOFAR - Opening up a new window on the Universe
Authors: H.J.A. Rottgering, R. Braun, P. D. Barthel, M. P. van Haarlem, G. K. Miley, R. Morganti, I. Snellen, H. Falcke, A.G. de Bruyn, R. B. Stappers, W.H.W.M. Boland, H.R. Butcher, E.J. de Geus, L. Koopmans, R. Fender, J. Kuijpers, R.T. Schilizzi, C. Vogt, R.A.M.J. Wijers, M. Wise, W.N. Brouw, J.P. Hamaker, J.E. Noordam, T. Oosterloo, L. Bahren, M.A. Brentjens, S.J. Wijnholds, J.D. Bregman, W.A. van Cappellen, A.W. Gunst, G.W. Kant, J. Reitsma, K. van der Schaaf, C.M. de Vos
(revised v2)

LOFAR, the Low Frequency Array, is a next-generation radio telescope that is being built in Northern Europe and expected to be fully operational at the end of this decade. It will operate at frequencies from 15 to 240 MHz (corresponding to wavelengths of 20 to 1.2 m). Its superb sensitivity, high angular resolution, large field of view and flexible spectroscopic capabilities will represent a dramatic improvement over previous facilities at these wavelengths. As such, LOFAR will carry out a broad range of fundamental astrophysical studies.
The design of LOFAR has been driven by four fundamental astrophysical applications: (i) The Epoch of Reionisation, (ii) Extragalactic Surveys and their exploitation to study the formation and evolution of clusters, galaxies and black holes, (iii) Transient Sources and their association with high energy objects such as gamma ray bursts, and (iv) Cosmic Ray showers and their exploitation to study the origin of ultra-high energy cosmic rays. In this conference the foreseen LOFAR work on the epoch of reionisation has been covered by de Bruyn and on cosmic ray showers by Falcke.
During this contribution we will first present the LOFAR project with an emphasis on the challenges faced when carrying out sensitive imaging at low radio frequencies. Subsequently, we will discuss LOFAR's capabilities to survey the low-frequency radio sky. Main aims for the planned surveys are studies of z>6 radio galaxies, diffuse emission associated with distant clusters and starbursting galaxies at z>2.

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