PS1-10bzj: A FAST, HYDROGEN-POOR SUPERLUMINOUS SUPERNOVA IN A METAL-POOR HOST GALAXY

We present observations and analysis of PS1-10bzj, a superluminous supernova (SLSN) discovered in the Pan-STARRS Medium Deep Survey at a redshift z = 0.650. Spectroscopically, PS1-10bzj is similar to the hydrogenpoor SLSNe 2005ap and SCP 06F6, though with a steeper rise and lower peak luminosity (M-bol similar or equal to -21.4 mag) than previous events. We construct a bolometric light curve, and show that while PS1-10bzj's energetics were less extreme than previous events, its luminosity still cannot be explained by radioactive nickel decay alone. We explore both a magnetar spin-down and circumstellar interaction scenario and find that either can fit the data. PS1-10bzj is located in the Extended Chandra Deep Field South and the host galaxy is imaged in a number of surveys, including with the Hubble Space Telescope. The host is a compact dwarf galaxy (MB approximate to -18 mag, diameter less than or similar to 800 pc), with a low stellar mass (M-* approximate to 2.4 x 10(7) M-circle dot), young stellar population (tau(*) approximate to 5 Myr), and a star formation rate of similar to 2-3 M-circle dot yr(-1). The specific star formation rate is the highest seen in an SLSN host so far (similar to 100 Gyr(-1)). We detect the [OIII] lambda 4363 line, and find a low metallicity: 12 + (O/H) = 7.8 +/- 0.2 (similar or equal to 0.1 Z(circle dot)). Together, this indicates that at least some of the progenitors of SLSNe come from young, low-metallicity populations.