2022ApJ...931...32Y

We present optical imaging and spectroscopy of SN 2018lfe, which we classify as a Type I superluminous supernova (SLSN-I) at a redshift of z = 0.3501 ± 0.0004 with a peak absolute magnitude of M_r = -22.1 ± 0.1 mag, one of the brightest SLSNe discovered. SN 2018lfe was identified for follow-up using our FLEET machine-learning pipeline. Both the light curve and the spectra of SN 2018lfe are consistent with the broad population of SLSNe. We fit the light curve with a magnetar central engine model and find an ejecta mass of M_ej ≃ 3.8 M_☉, a magnetar spin period of P ≃ 2.9 ms, and a magnetic field strength of B_⊥ ≃ 2.8 x 10¹⁴ G. The magnetic field strength is near the top of the distribution for SLSNe, while the spin period and ejecta mass are near the median values of the distribution for SLSNe. From late-time imaging and spectroscopy we find that the host galaxy of SN 2018lfe has an absolute magnitude of M_r = -17.85 ± 0.24, (L_B = 0.029 ± 0.007L*), and an inferred metallicity of Z ≃ 0.3 Z_☉ and star formation rate of ≃0.8 M_☉ yr^–1.