We present results from a radio survey for variable and transient sources on 15-min timescales, using the Australian SKA Pathfinder (ASKAP) pilot surveys. The pilot surveys consist of 505 h of observations conducted at around 1 GHz observing frequency, with a total sky coverage of 1476 deg2. Each observation was tracked for approximately 8-10h, with a typical rms sensitivity of ∼30 μjy/beam and an angular resolution of ∼12 arcsec. The variability search was conducted within each 8-10h observation on a 15-min timescale. We detected 38 variable and transient sources. Seven of them are known pulsars, including an eclipsing millisecond pulsar, PSR J2039−5617. Another eight sources are stars, only one of which has been previously identified as a radio star. For the remaining 23 objects, 22 are associated with active galactic nuclei or galaxies (including the five intra-hour variables that have been reported previously), and their variations are caused by discrete, local plasma screens. The remaining source has no multi-wavelength counterparts and is therefore yet to be identified. This is the first large-scale radio survey for variables and transient sources on minute timescales at a sub-mJy sensitivity level. We expect to discover ∼1 highly variable source per day using the same technique on the full ASKAP surveys.
@article{arxiv.2306.04263,
title = {Radio Variable and Transient Sources on Minute Timescales in the ASKAP Pilot Surveys},
author = {Yuanming Wang and Tara Murphy and Emil Lenc and Louis Mercorelli and Laura Driessen and Joshua Pritchard and Baoqiang Lao and David L. Kaplan and Tao An and Keith W. Bannister and George Heald and 5 Shuoying Lu and Artem Tuntsov and Mark Walker and Andrew Zic},
journal= {arXiv preprint arXiv:2306.04263},
year = {2023}
}
Comments
20 pages, 11 figures; accepted for publication in MNRAS