Fast blue optical transient
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.
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Comparison of explosion scenarios of supernovae (SN), gamma-ray bursts (GRB) and fast blue optical transients (FBOT)
Bolometric luminosity of AT2018cow, compared against other fast transients, showing a very rapid evolution and high peak luminosity
Optical spectra of AT2018cow, revealing a hot blackbody emission, with significant flux bluewards of (4000 Å)
X-ray luminosity of FBOTs compared with other astronomical transients
Star formation rate diagram for FBOTs.
