John McKean

Publications (4)0 Total impact

• Source

  Available from: Glenn J. White

  Article: LOFAR and APERTIF Surveys of the radio sky: probing shocks and magnetic fields in galaxy clusters

  Huub Röttgering, Jose Afonso, Peter Barthel, Fabien Batejat, Philip Best, Annalisa Bonafede, Marcus Brüggen, Gianfranco Brunetti, Krzysztof Chy.zy, John Conway, [......], Roberto Pizzo, David Rafferty, Alexander Shulevski, Cyril Tasse, Ilse Bemmel, Bas Tol, Reinout Weeren, Marc Verheijen, Glenn White, Michael Wise
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  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. The revolutionary APERTIFphased arrays that are about to be installed on the Westerbork radio telescope (WSRT) will dramatically increase the survey speed for the WSRT. Combined surveys with these two facilities will deeply chart the northern sky over almost two decades in radio frequency from $sim$15 up to 1400 MHz. Here we briefly describe some of the capabilities of these new facilities and what radio surveys are planned to study fun-damental issues related to the formation and evolution of galaxies and clusters of galaxies. In the second part we briefly review some recent observational results directly showing that diffuse radio emission in clusters traces shocks due to cluster mergers. As these diffuse radio sources are relatively bright at low frequencies, LOFAR should be able to detect thousands of such sources up to the epoch of cluster formation. This will allow addressing many question about the origin and evolution of shocks and magnetic fields in clusters. At the end we briefly review some of the first and very preliminary LOFAR results on clusters.
  Journal of Astrophysics and Astronomy. 07/2011; 32:557-566.
• Source

  Available from: Michael Ryan Bell

  Article: LOFAR: Recent imaging results & future prospects

  George Heald, Michael R. Bell, Andreas Horneffer, André R. Offringa, Roberto Pizzo, Sebastiaan van der Tol, Reinout J. van Weeren, Joris E. van Zwieten, James M. Anderson, Rainer Beck, [......], Emanuela Orrù, David Rafferty, Huub Röttgering, Anna Scaife, Aleksandar Shulevski, Carlos Sotomayor, Cyril Tasse, Monica Trasatti, Olaf Wucknitz, on behalf of the LOFAR Collaboration
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  ABSTRACT: The Low Frequency Array (LOFAR) is under construction in the Netherlands and in several surrounding European countries. In this contribution, we describe the layout and design of the telescope, with a particular emphasis on the imaging characteristics of the array when used in its "standard imaging" mode. After briefly reviewing the calibration and imaging software used for LOFAR image processing, we show some recent results from the ongoing imaging commissioning efforts. We conclude by summarizing future prospects for the use of LOFAR in observing the little-explored low frequency Universe.
  06/2011;
• Source

  Available from: Fabien Batejat

  Article: LOFAR: Early imaging results from commissioning for Cygnus A

  John McKean, Louise Ker, Reinout J. van Weeren, Fabien Batejat, Laura Birzan, Annalisa Bonafede, John Conway, Francesco De Gasperin, Chiara Ferrari, George Heald, [......], Roberto Pizzo, David Rafferty, Huub Rottgering, Aleksandar Shulevski, Cyril Tasse, Sebastiaan van der Tol, Ilse van Bemmel, Ger van Diepen, Joris E. van Zwieten, for the LOFAR Collaboration
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  ABSTRACT: The Low Frequency Array (LOFAR) will operate between 10 and 250 MHz, and will observe the low frequency Universe to an unprecedented sensitivity and angular resolution. The construction and commissioning of LOFAR is well underway, with over 27 of the Dutch stations and five International stations routinely performing both single-station and interferometric observations over the frequency range that LOFAR is anticipated to operate at. Here, we summarize the capabilities of LOFAR and report on some of the early commissioning imaging of Cygnus A.
  06/2011;
• Source

  Available from: G. Macario

  Article: Progress with the LOFAR Imaging Pipeline

  George Heald, John McKean, Roberto Pizzo, Ger van Diepen, Joris E. van Zwieten, Reinout J. van Weeren, David Rafferty, Sebastiaan van der Tol, Laura Birzan, Aleksandar Shulevski, John Swinbank, Emanuela Orru, Francesco De Gasperin, Louise Ker, Annalisa Bonafede, Giulia Macario, Chiara Ferrari, on behalf of the LOFAR Collaboration
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  ABSTRACT: One of the science drivers of the new Low Frequency Array (LOFAR) is large-area surveys of the low-frequency radio sky. Realizing this goal requires automated processing of the interferometric data, such that fully calibrated images are produced by the system during survey operations. The LOFAR Imaging Pipeline is the tool intended for this purpose, and is now undergoing significant commissioning work. The pipeline is now functional as an automated processing chain. Here we present several recent LOFAR images that have been produced during the still ongoing commissioning period. These early LOFAR images are representative of some of the science goals of the commissioning team members. Comment: 11 pages, 6 figures. Accepted for publication in proceedings of "ISKAF2010 Science Meeting", PoS(ISKAF2010)057
  08/2010;