Rapidly evolving transients in the Dark Energy Survey

• Published in: arXiv.org 2018-08
• Main Authors: Pursiainen, M, Childress, M, Smith, M, Prajs, S, Sullivan, M, Davis, T M, Foley, R J, Asorey, J, Calcino, J, Carollo, D, Curtin, C, D'Andrea, C B, Glazebrook, K, Gutierrez, C, Hinton, S R, Hoormann, J K, Inserra, C, Kessler, R, King, A, Kuehn, K, Lewis, G F, Lidman, C, Macaulay, E, Möller, A, Nichol, R C, Sako, M, Sommer, N E, Swann, E, Tucker, B E, Uddin, S A, Wiseman, P, Zhang, B, Abbott, T M C, Abdalla, F B, Allam, S, Annis, J, Avila, S, Brooks, D, Buckley-Geer, E, Burke, D L, A Carnero Rosell, M Carrasco Kind, Carretero, J, Castander, F J, Cunha, C E, Davis, C, De Vicente, J, Diehl, H T, Doel, P, Eifler, T F, Flaugher, B, Fosalba, P, Frieman, J, García-Bellido, J, Gruen, D, Gruendl, R A, Gutierrez, G, Hartley, W G, Hollowood, D L, Honscheid, K, James, D J, Jeltema, T, Kuropatkin, N, Li, T S, Lima, M, Maia, M A G, Martini, P, Menanteau, F, Ogando, R L C, Plazas, A A, Roodman, A, Sanchez, E, Scarpine, V, Schindler, R, Smith, R C, Soares-Santos, M, Sobreira, F, Suchyta, E, Swanson, M E C, Tarle, G, Tucker, D L, Walker, A R
• Format: Article
• Language: English
• Subjects: Blackbody; Collapse; Dark energy; Ejecta; Galaxies; Light curve; Photometry; Photosphere; Red shift; Sky surveys (astronomy); Star formation; Stellar evolution; Stellar winds
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.1803.04869

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 \(\lesssim 10\) d and exponential decline in \(\lesssim30\) 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 (\(0.05-22.25\)). The multiband photometry is well fit by a blackbody up to few weeks after peak. The events appear to be hot (\(T\approx10000-30000\) K) and large (\(R\approx 10^{14}-2\cdot10^{15}\) 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.