SN2018kzr: a rapidly declining transient from the destruction of a white dwarf McBrien, Owen Galvany, Lluís We present SN2018kzr, the fastest declining supernova-like transient, second only to the kilonova, AT2017gfo. SN2018kzr is characterized by a peak magnitude of Mr=−17.98, peak bolometric luminosity of ∼1.4×1043erg s−1 and a rapid decline rate of 0.48±0.03 mag day-1 in the r band. The bolometric luminosity evolves too quickly to be explained by pure 56Ni heating, necessitating the inclusion of an alternative powering source. Incorporating the spin-down of a magnetized neutron star adequately describes the lightcurve and we estimate a small ejecta mass of Mej=0.10±0.05 M⊙. Our spectral modelling suggests the ejecta is composed of intermediate mass elements including O, Si and Mg and trace amounts of Fe-peak elements, which disfavours a binary neutron star merger. We discuss three explosion scenarios for SN2018kzr, given the low ejecta mass, intermediate mass element composition and the high likelihood of additional powering - core collapse of an ultra-stripped progenitor, the accretion induced collapse of a white dwarf and the merger of a white dwarf and neutron star. The requirement for an alternative input energy source favours either the accretion induced collapse with magnetar powering or a white dwarf - neutron star merger with energy from disk wind shocks. 2019-12-19T10:36:20Z 2019-12-19T10:36:20Z 2019-09-11 info:eu-repo/semantics/article McBrien, O. R., Smartt, S. J., Chen, T. W., Inserra, C., Gillanders, J. H., Sim, S. A., ... & Gromadzki, M. (2019). SN2018kzr: a rapidly declining transient from the destruction of a white dwarf. The Astrophysical Journal Letters, 885(1), L23. http://hdl.handle.net/10481/58424 eng http://creativecommons.org/licenses/by-nc-nd/3.0/es/ info:eu-repo/semantics/openAccess Atribución-NoComercial-SinDerivadas 3.0 España IOP Publishing