In astronomy, a fast blue optical transient (FBOT), or more specifically, luminous fast blue optical transient (LFBOT), is an explosive transient event similar to supernovae and gamma-ray bursts with high optical luminosity, rapid evolution, and predominantly blue emission. The origins of such explosions are currently unclear, with events occurring at not more than 0.1% of the typical core-collapse supernova rate. This class of transients initially emerged from large sky surveys at cosmological distances, yet in recent years a small number have been discovered in the local Universe, most notably AT 2018cow.
The precise definition of what constitutes a 'fast blue optical transient' is currently contentious in the literature, largely defined by the observational properties rather than the underlying mechanisms/objects. Even within the class, growing samples of candidates are beginning to reveal significant variation in properties when the objects are studied in greater detail, potentially indicative of different progenitor channels or explosion mechanisms.
List +TransientReportedDateObservatoryNotesAT 2018cow201816 June 2018ATLAS-HKO"The Cow", the most local FBOT known, and the event with the richest dataset, making it a prototype of the class. Peak luminosity erg s⁻¹, exceeding that of superluminous supernovaeZTF18abvkwla (AT 2018lug)202012 September 2018Zwicky Transient Facility"The Koala" Blackbody temperature of over 40,000 Kelvin at peakCSS161010202010 October 2016CRTSShows mildly relativistic (55% the speed of light) mass outflowsAT 2020xnd (ZTF20acigmel)202112 October 2020Zwicky Transient Facility"The Camel"AT 2020mrf202212 June 2020Spektr-RG, Zwicky Transient Facility200 times more luminous on the X-ray spectrum at its peak than AT 2018cow and CSS161010AT 2022tsd20237 September 2022Neil Gehrels Swift Observatory, Zwicky Transient Facility"The Tasmanian Devil", minutes-duration optical flares suggestive of a NS/BH from a failed supernova event.AT 2023fhn202310 April 2023Zwicky Transient Facility"The Finch" or "The Fawn"AT 2023vth (ZTF23ableqsp)Transient Name Server entry for AT 2023vth. Retrieved 22 November 2023.202318 October 2023Zwicky Transient FacilityFirst FBOT to be labelled as such on the Transient Name Server.AT 2024wpp202426 September 2024Zwicky Transient Facility"The wasp" (tentatively), brightest FBOT at time of discovery with peak at −21.9 magAT 2025wap (ZTF25abkgjzb)202521 August 2025Zwicky Transient Facility
See also Gamma-ray burst Intermediate luminosity optical transient Supernova
References
External links (2016; Harvard University)