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Rapidly evolving transients in the Dark Energy Survey

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We present the results of a search for rapidly evolving transients in the Dark Energy Survey Supernova Programme. These events are characterized by fast light curve evolution (rise to peak in ≲10 d and exponential decline in ≲30 d after peak). We discovered 72 events, including 37 transients with a spectroscopic redshift from host galaxy spectral features. The 37 events increase the total number of rapid optical transients by more than factor of two. They are found at a wide range of redshifts (0.05<z<1.56) and peak brightnesses (−15.75>Mg>−22.25). The multiband photometry is well fit by a blackbody up to few weeks after peak. The events appear to be hot (T≈10000−30000 K) and large (R≈1014−2⋅1015 cm) at peak, and generally expand and cool in time, though some events show evidence for a receding photosphere with roughly constant temperature. Spectra taken around peak are dominated by a blue featureless continuum consistent with hot, optically thick ejecta. We compare our events with a previously suggested physical scenario involving shock breakout in an optically thick wind surrounding a core-collapse supernova (CCSNe), we conclude that current models for such a scenario might need an additional power source to describe the exponential decline. We find these transients tend to favor star-forming host galaxies, which could be consistent with a core-collapse origin. However, more detailed modeling of the light curves is necessary to determine their physical origin.
Original languageEnglish
Pages (from-to)894-917
Number of pages24
JournalMonthly Notices of the Royal Astronomical Society
Volume481
Issue number1
Early online date29 Aug 2018
DOIs
Publication statusPublished - 1 Nov 2018

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    Rights statement: This article has been accepted for publication in MNRAS © 2018 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.

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