Probing the extragalactic fast transient sky at minute timescales with DECam
Links to Fileshttps://arxiv.org/abs/1903.11083
MetadataShow full item record
Type of Work20 pages
journal articles preprints
Citation of Original PublicationIgor Andreoni, et.al, Probing the extragalactic fast transient sky at minute timescales with DECam, Astrophysics, High Energy Astrophysical Phenomena, 2019, https://arxiv.org/abs/1903.11083
RightsThis item is likely protected under Title 17 of the U.S. Copyright Law. Unless on a Creative Commons license, for uses protected by Copyright Law, contact the copyright holder or the author.
Searches for optical transients are usually performed with a cadence of days to weeks, optimised for supernova discovery. The optical fast transient sky is still largely unexplored, with only a few surveys to date having placed meaningful constraints on the detection of extragalactic transients evolving at sub-hour timescales. Here, we present the results of deep searches for dim, minute-timescale extragalactic fast transients using the Dark Energy Camera, a core facility of our all-wavelength and all-messenger Deeper, Wider, Faster programme. We used continuous 20 s exposures to systematically probe timescales down to 1.17 minutes at magnitude limits g > 23 (AB), detecting hundreds of transient and variable sources. Nine candidates passed our strict criteria on duration and non-stellarity, 5 of which could later be classified as flare stars, but 4 of which have more unsure classification. Searches for fast radio burst and gamma-ray counterparts during simultaneous multi-facility observations yielded no counterparts to those 4 optical transients. Also, no long-term variability was detected with pre-imaging and follow-up observations using the SkyMapper optical telescope. We place (conservative) upper limits and (optimistic) measurements of minute-timescale fast optical transient rates for a range of depths and timescales. Finally, we demonstrate that optical g-band light curve behaviour alone cannot discriminate between confirmed extragalactic fast transients such as prompt GRB flashes and Galactic stellar flares.