Search

Rapidly evolving transients form a new class of transients that show shorter timescales of light curves than those of typical core-collapse and thermonuclear supernovae. We performed a systematic search for rapidly evolving transients using deep data taken with the Hyper Suprime-Cam Subaru Strategic Program Transient Survey. By measuring the timescales of the light curves of 1824 transients, we identified five rapidly evolving transients. Our samples are found in a wide range of redshifts (0.3 ≤ z ≤ 1.5) and peak absolute magnitudes (−17 ≥ Mi ≥ −20). The light-curve properties are similar to those of the previously discovered rapidly evolving transients. They show a relatively blue spectral energy distribution, with the best-fit blackbody of 8000–18,000 K. We show that some of the transients require power sources other than the radioactive decays of 56Ni because of their high peak luminosities and short timescales. The host galaxies of all of the samples are star-forming galaxies, suggesting a massive star origin for the rapidly evolving transients. The event rate is roughly estimated to be ∼4000 events yr−1 Gpc−3, which is about 1% of core-collapse supernovae. [ABSTRACT FROM AUTHOR]