e-Article
Probing the extragalactic fast transient sky at minute timescales with DECam
Document Type
Working Paper
Author
Andreoni, Igor; Cooke, Jeffrey; Webb, Sara; Rest, Armin; Pritchard, Tyler A.; Caleb, Manisha; Chang, Seo-Won; Farah, Wael; Lien, Amy; Möller, Anais; Ravasio, Maria Edvige; Abbott, Timothy M. C.; Bhandari, Shivani; Cucchiara, Antonino; Flynn, Christopher M.; Jankowski, Fabian; Keane, Evan F.; Moriya, Takashi J.; Onken, Christopher; Parthasarathy, Aditya; Price, Daniel C.; Petroff, Emily; Ryder, Stuart; Vohl, Dany; Wolf, Christian
Source
Monthly Notices of the Royal Astronomical Society (2020), Volume 491, Issue 4, p.5852-5866
Subject
Language
Abstract
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 20s 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, all of which could be classified as flare stars based on deep multi-band imaging. Searches for fast radio burst and gamma-ray counterparts during simultaneous multi-facility observations yielded no counterparts to the optical transients. Also, no long-term variability was detected with pre-imaging and follow-up observations using the SkyMapper optical telescope. We place upper limits for 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.
Comment: Published in MNRAS
Comment: Published in MNRAS