Two years of optical and NIR observations of the superluminous supernova UID 30901 discovered by the UltraVISTA SN survey

Abstract

We present deep optical and near-infrared photometry of UID 30901, a superluminous supernova (SLSN) discovered during the UltraVISTA survey. The observations were obtained with VIRCAM ($YJH{K}_s$) mounted on the VISTA telescope, DECam ($griz$) on the Blanco telescope, and SUBARU Hyper Suprime-Cam (HSC; $grizy$). These multi-band observations comprise +700 days making UID 30901 one of the best photometrically followed SLSNe to date. The host galaxy of UID 30901 is detected in a deep HST F814W image with an AB magnitude of $27.3\pm 0.2$. While no spectra exist for the SN or its host galaxy, we perform our analysis assuming $z=0.37$, based on the photometric redshift of a possible host galaxy found at a projected distance of 7 kpc. Fitting a blackbody to the observations, the radius, temperature, and bolometric light curve are computed. We find a maximum bolometric luminosity of $5.4\pm 0.34\times 10^{43}$ erg s${}^{-1}$. A flattening in the light curve beyond 600 days is observed and several possible causes are discussed. We find the observations to clearly favour a SLSN type I, and plausible power sources such as the radioactive decay of ${}^{56}$Ni and the spin-down of a magnetar are compared to the data. We find that the magnetar model yields a good fit to the observations with the following parameters: a magnetic field $B=1.4\pm 0.3\times 10^{14}G$, spin period of $P=6.0\pm 0.1ms$ and ejecta mass $M_{ej}=11.9_{-6.4}^{+4.8}{M}_{\odot }$.

22 pages, 15 figures, Accepted for publication in MNRAs