Abstract
We present a survey for transient and variable sources, on time-scales from 28 s to ~1 yr, using the Murchison Widefield Array (MWA) at 182 MHz. Down to a detection threshold of 0.285 Jy, no transient candidates were identified, making this the most constraining low-frequency survey to date and placing a limit on the surface density of transients of <4.1 × 10-7 deg-2 for the shortest time-scale considered. At these frequencies, emission from Fast Radio Bursts (FRBs) is expected to be detectable in the shortest time-scale images without any corrections for interstellar or intergalactic dispersion. At an FRB limiting flux density of 7980 Jy, we find a rate of <82 FRBs per sky per day for dispersion measures <700 pc cm-3. Assuming a cosmological population of standard candles, our rate limits are consistent with the FRB rates obtained by Thornton et al. if they have a flat spectral slope. Finally, we conduct an initial variability survey of sources in the field with flux densities ≥ 0.5 Jy and identify no sources with significant variability in their light curves. However, we note that substantial further work is required to fully characterize both the short-term and low-level variability within this field.
Original language | English (US) |
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Pages (from-to) | 3506-3522 |
Number of pages | 17 |
Journal | Monthly Notices of the Royal Astronomical Society |
Volume | 458 |
Issue number | 4 |
DOIs | |
State | Published - Mar 17 2016 |
Keywords
- Catalogues
- Instrumentation: Interferometers
- Radio continuum: General
- Techniques: Image processing
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science