LOFAR MSSS: Detection of a low-frequency radio transient in 400 h of monitoring of the North Celestial Pole

A. J. Stewart, R. P. Fender, Jess W Broderick, Tom E Hassall, T. Muñoz-Darias, Antonia Rowlinson, John D Swinbank, Tim D Staley, Gijs J Molenaar, Bart Scheers, T. L. Grobler, Malgorzata Pietka, George Heald, John P McKean, M. E. Bell, Annalisa Bonafede, Rene P Breton, Dario Carbone, Yvette N Cendes, A. O. ClarkeStephane Corbel, Francesco de Gasperin, J. Eislöffel, Heino Falcke, Belinda C. Ferrari, J. M. Grießmeier, Martin J Hardcastle, V. Heesen, Jason W T Hessels, Andreas Horneffer, Marco Iacobelli, Peter G Jonker, Aris Karastergiou, G. Kokotanekov, Vlad I Kondratiev, Masaya Kuniyoshi, Casey J Law, Joeri van Leeuwen, Sera B Markoff, James C A Miller-Jones, David Declan Mulcahy, Emanuela Orru, Mamta Pandey-Pommier, L. Pratley, E. Rol, H. J.A. Röttgering, Anna M M Scaife, Alexander Shulevski, C. A. Sobey, Benjamin W Stappers, Cyril Tasse, Jeremy A Horst, S. van Velzen, Reinout J van Weeren, Ralph A M J Wijers, Rudy A D Wijnands, Helen M Wise, Philippe Zarka, Anastasia Alexov, J. Anderson, Ashish Asgekar, Ian M Avruch, Mark J Bentum, Gianni Bernardi, John P Best, Frank Breitling, M. Brüggen, Harvey Raymond Butcher, Benedetta Ciardi, John E Conway, Arthur Corstanje, E. de Geus, Adam Travis Deller, S. Duscha, Wilfred Frieswijk, M. A. Garrett, Andre W Gunst, Michael P van Haarlem, Matthias Hoeft, J. Hörandel, E. Juette, Geert Kuper, Matt Loose, Peter Maat, Rebecca A McFadden, Derek McKay-Bukowski, J. Moldon, Harm Munk, M. J. Norden, Harm Paas, A. G. Polatidis, Andrew D Schwarz, Jurjen Sluman, Oleg Smirnov, Matthias Steinmetz, Satyendra Thoudam, Maria Carmen Toribio, R Vermeulen, Christian Vocks, Stefan J Wijnholds, Olaf Wucknitz, Sarod Yatawatta

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Abstract

We present the results of a four-month campaign searching for low-frequency radio transients near the North Celestial Pole with the Low-Frequency Array (LOFAR), as part of the Multifrequency Snapshot Sky Survey (MSSS). The data were recorded between 2011 December and 2012 April and comprised 2149 11-min snapshots, each covering 175 deg2. We have found one convincing candidate astrophysical transient, with a duration of a few minutes and a flux density at 60 MHz of 15-25 Jy. The transient does not repeat and has no obvious optical or high-energy counterpart, as a result of which its nature is unclear. The detection of this event implies a transient rate at 60 MHz of 3.9-3.7 +14.7 × 10-4 d-1 deg-2, and a transient surface density of 1.5 × 10-5 deg-2, at a 7.9-Jy limiting flux density and ~10-min time-scale. The campaign data were also searched for transients at a range of other time-scales, from 0.5 to 297 min, which allowed us to place a range of limits on transient rates at 60MHz as a function of observation duration.

Original languageEnglish
Pages (from-to)2321-2342
Number of pages22
JournalMonthly Notices of the Royal Astronomical Society
Volume456
Issue number3
DOIs
Publication statusPublished - 1 Mar 2016

Keywords

  • Instrumentation: interferometers
  • Radio continuum: general
  • Techniques: image processing

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