Fast blue optical transient

{{short description|Astronomical observation}}

{{use dmy dates |date=May 2020}}

File:FBOTemissions.jpg

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.{{cite news |last=O"Callaghan |first=Jonathan |title=A Cow, a Camel and a Finch Exploded in Space. What Is Going On? - Astronomers have yet to determine the cause of luminous fast blue optical transients, and the latest they have detected is raising even more questions. |url=https://www.nytimes.com/2023/07/19/science/explosions-black-holes-lfbots.html |date=19 July 2023 |work=The New York Times |url-status=live |archiveurl=https://web.archive.org/web/20230720000625/https://www.nytimes.com/2023/07/19/science/explosions-black-holes-lfbots.html |archivedate=20 July 2023 |accessdate=19 July 2023 }} The origins of such explosions are currently unclear, with events occurring at not more than 0.1% of the typical core-collapse supernova rate.{{Cite journal|last1=Ho|first1=Anna Y. Q.|last2=Perley|first2=Daniel A.|last3=Kulkarni|first3=S. R.|last4=Dong|first4=Dillon Z. J.|last5=De|first5=Kishalay|last6=Chandra|first6=Poonam|last7=Andreoni|first7=Igor|last8=Bellm|first8=Eric C.|last9=Burdge|first9=Kevin B.|last10=Coughlin|first10=Michael|last11=Dekany|first11=Richard|date=2020-05-26|title=The Koala: A Fast Blue Optical Transient with Luminous Radio Emission from a Starburst Dwarf Galaxy atz= 0.27|journal=The Astrophysical Journal|language=en|volume=895|issue=1|pages=49|doi=10.3847/1538-4357/ab8bcf|arxiv=2003.01222|bibcode=2020ApJ...895...49H|s2cid=211817823|issn=1538-4357 |doi-access=free }} This class of transients initially emerged from large sky surveys at cosmological distances,{{Cite journal |last1=Drout |first1=M. R. |last2=Chornock |first2=R. |last3=Soderberg |first3=A. M. |last4=Sanders |first4=N. E. |last5=McKinnon |first5=R. |last6=Rest |first6=A. |last7=Foley |first7=R. J. |last8=Milisavljevic |first8=D. |last9=Margutti |first9=R. |last10=Berger |first10=E. |last11=Calkins |first11=M. |last12=Fong |first12=W. |last13=Gezari |first13=S. |last14=Huber |first14=M. E. |last15=Kankare |first15=E. |date=2014-09-19 |title=Rapidly-Evolving and Luminous Transients from Pan-STARRS1 |journal=The Astrophysical Journal |volume=794 |issue=1 |pages=23 |doi=10.1088/0004-637X/794/1/23 |arxiv=1405.3668 |bibcode=2014ApJ...794...23D |issn=1538-4357}}{{Cite journal |last1=Pursiainen |first1=M. |last2=Childress |first2=M. |last3=Smith |first3=M. |last4=Prajs |first4=S. |last5=Sullivan |first5=M. |last6=Davis |first6=T. M. |last7=Foley |first7=R. J. |last8=Asorey |first8=J. |last9=Calcino |first9=J. |last10=Carollo |first10=D. |last11=Curtin |first11=C. |last12=D'Andrea |first12=C. B. |last13=Glazebrook |first13=K. |last14=Gutierrez |first14=C. |last15=Hinton |first15=S. R. |date=2018-11-21 |title=Rapidly evolving transients in the Dark Energy Survey |journal=Monthly Notices of the Royal Astronomical Society |volume=481 |issue=1 |pages=894–917 |doi=10.1093/mnras/sty2309 |doi-access=free |arxiv=1803.04869 |issn=0035-8711}} 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{{Cite journal |last1=Ho |first1=Anna Y. Q. |last2=Perley |first2=Daniel A. |last3=Gal-Yam |first3=Avishay |last4=Lunnan |first4=Ragnhild |last5=Sollerman |first5=Jesper |last6=Schulze |first6=Steve |last7=Das |first7=Kaustav K. |last8=Dobie |first8=Dougal |last9=Yao |first9=Yuhan |last10=Fremling |first10=Christoffer |last11=Adams |first11=Scott |last12=Anand |first12=Shreya |last13=Andreoni |first13=Igor |last14=Bellm |first14=Eric C. |last15=Bruch |first15=Rachel J. |date=2023-06-01 |title=A Search for Extragalactic Fast Blue Optical Transients in ZTF and the Rate of AT2018cow-like Transients |journal=The Astrophysical Journal |volume=949 |issue=2 |pages=120 |doi=10.3847/1538-4357/acc533 |arxiv=2105.08811 |issn=0004-637X |doi-access=free |bibcode=2023ApJ...949..120H }} 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.