Modern wide-field high-cadence surveys have revealed the significant diversity of optical transient phenomena in their luminosity and timescale distributions,which led to the discovery of some mysterious fast optical ...Modern wide-field high-cadence surveys have revealed the significant diversity of optical transient phenomena in their luminosity and timescale distributions,which led to the discovery of some mysterious fast optical transients(FOTs).These FOTs can usually rise and decline remarkably in a timescale of a few days to weeks,which are obviously much rapider than ordinary supernovae.SN2019 bkc/ATLAS19 dqr is one of the fastest detected FOTs so far and,meanwhile,it was found to be unassociated with a host galaxy.These discoveries provide a good chance to explore the possible origins of FOTs.So,we model the light curves of SN 2019 bkc in details.It is found that SN 2019 bkc can be well explained by the thermal emission of an explosion ejecta that is powered by a long-lasting central engine.The engine could be a spinning-down millisecond magnetar or a fallback accretion onto a compact object.Combining the engine property,the mass of the ejecta,and the hostlessness of SN 2019 bkc,we suggest that this FOT is likely to originate from a merger of a white dwarf and a neutron star.展开更多
基金supported by the Ministry of Science and Technology of the People’s Republic of China (2020SKA0120300)the National Natural Science Foundation of China (Grant Nos.11822302 and 11833003)。
文摘Modern wide-field high-cadence surveys have revealed the significant diversity of optical transient phenomena in their luminosity and timescale distributions,which led to the discovery of some mysterious fast optical transients(FOTs).These FOTs can usually rise and decline remarkably in a timescale of a few days to weeks,which are obviously much rapider than ordinary supernovae.SN2019 bkc/ATLAS19 dqr is one of the fastest detected FOTs so far and,meanwhile,it was found to be unassociated with a host galaxy.These discoveries provide a good chance to explore the possible origins of FOTs.So,we model the light curves of SN 2019 bkc in details.It is found that SN 2019 bkc can be well explained by the thermal emission of an explosion ejecta that is powered by a long-lasting central engine.The engine could be a spinning-down millisecond magnetar or a fallback accretion onto a compact object.Combining the engine property,the mass of the ejecta,and the hostlessness of SN 2019 bkc,we suggest that this FOT is likely to originate from a merger of a white dwarf and a neutron star.
