Discovery of peculiar X-ray characteristics of AT2018cow with Swift Liliana Rivera Sandoval liliana.rivera@ttu.edu Collaborators: Tom Maccarone (TTU) Alessandra Corsi (TTU) Peter Brown (Texas A&M) David Pooley (Trinity University) Craig Wheeler (UT-Austin) Artistic impression of a super luminous supernova, NASA

NASA’s Goddard Space Flight Center

AT2018cow Swift trigger Day 0 ATLAS Discovery Accreting white dwarf Day 0 ATLAS Discovery Day 3 Swift observations: very blue object, X-ray bright Companion star Discovery: 16 June 2018 Swift optical Swift UV First Swift data: 19 June 2018

The Discovery of X-ray Variability Some optical spectra —> Core collapse Supernovae Interaction between the supernova ejecta and a non-uniform circum-stellar medium —> X-rays spikes Massive stars eject large amounts of mass Rivera Sandoval et al., 2018 AT2018cow location: spiral arm of star forming galaxy Credit: NASA, ESA, and the Hubble SM4 ERO Team

No significant spectral evolution in low energy (0.3-10 keV) X-rays X-ray Spectra Spectral evolution X-ray spectrum No significant spectral evolution in low energy (0.3-10 keV) X-rays Rivera Sandoval et al., 2018

Contact: Liliana Rivera Sandoval, liliana.rivera@ttu.edu Take-Home Message Our early and extensive observations with Swift played an important role in the study of Fast Evolving Luminous Transients —> discovery of unprecedented characteristics. AT2018cow was a very blue, X-ray bright and fast-rise time transient. We discovered its peculiar X-ray luminosity variability. The low energy X-ray spectrum did not significantly change. Supernova ejecta + non-uniform circum-stellar medium may explain the Swift X-ray results. Contact: Liliana Rivera Sandoval, liliana.rivera@ttu.edu