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

Journal article

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 deg 2 . 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.

Authors: Stewart, A; Fender, R; Broderick, J; Hassall, T; Muñoz-Darias, T

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Oxford University Press
• Journal: Monthly Notices of the Royal Astronomical Society
• Volume: 456
• Issue: 3
• Pages: 2321-2342
• Publication date: 2016-03-01
• Acceptance date: 2015-11-26
• DOI: 10.1093/mnras/stv2797
• EISSN: 1365-2966
• ISSN: 0035-8711
• Keywords: Journal Article; instrumentation: interferometers; techniques: image processing; radio continuum: general; SBTMR