Studying the ultraviolet spectrum of the first spectroscopically confirmed supernova at redshift two

Smith, M, Sullivan, M, Nichol, R C, Galbany, L, D'Andrea, C B, Inserra, C, Lidman, C, Rest, A, Schirmer, M, Filippenko, A V, Zheng, W, Bradley Cenko, S, Angus, C R, Brown, P J, Davis, T M, Finley, D A, Foley, R J, González-Gaitán, S, Gutiérrez, C P, Kessler, R, Kuhlmann, S, Marriner, J, Möller, A, Nugent, P E, Prajs, S, Thomas, R, Wolf, R, Romer, A K, Zenteno, A, and others, and The DES Collaboration, (2018) Studying the ultraviolet spectrum of the first spectroscopically confirmed supernova at redshift two. Astrophysical Journal, 854 (37). pp. 1-14. ISSN 0004-637X

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We present observations of DES16C2nm, the first spectroscopically confirmed hydrogen-free superluminous supernova (SLSN-I) at redshift z » 2. DES16C2nm was discovered by the Dark Energy Survey (DES) Supernova Program, with follow-up photometric data from the Hubble Space Telescope, Gemini, and the European Southern Observatory Very Large Telescope supplementing the DES data. Spectroscopic observations confirm DES16C2nm to be at z = 1.998, and spectroscopically similar to Gaia16apd (a SLSN-I at z = 0.102), with a peak absolute magnitude of U =-  22.26 0.06. The high redshift of DES16C2nm provides a unique opportunity to study the ultraviolet (UV) properties of SLSNe-I. Combining DES16C2nm with 10 similar events from the literature, we show that there exists a homogeneous class of SLSNe-I in the UV (lrest » 2500 Å), with peak luminosities in the (rest-frame) U band, and increasing absorption to shorter wavelengths. There is no evidence that the mean photometric and spectroscopic properties of SLSNe-I differ between low (z < 1) and high redshift (z > 1), but there is clear evidence of diversity in the spectrum at lrest < 2000 Å, possibly caused by the variations in temperature between events. No significant correlations are observed between spectral line velocities and photometric luminosity. Using these data, we estimate that SLSNe-I can be discovered to z = 3.8 by DES. While SLSNe-I are typically identified from their blue observed colors at low redshift (z < 1), we highlight that at z > 2 these events appear optically red, peaking in the observer-frame z-band. Such characteristics are critical to identify these objects with future facilities such as the Large Synoptic Survey Telescope, Euclid, and the Wide-field Infrared Survey Telescope, which should detect such SLSNe-I to z = 3.5, 3.7, and 6.6, respectively.

Item Type: Article
Schools and Departments: School of Mathematical and Physical Sciences > Physics and Astronomy
Subjects: Q Science > QB Astronomy
Depositing User: Billy Wichaidit
Date Deposited: 05 Mar 2018 09:52
Last Modified: 05 Mar 2018 10:04

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Project NameSussex Project NumberFunderFunder Ref
University of Sussex Astronomy Consolidated Grant 2017-2020G2050STFC-SCIENCE AND TECHNOLOGY FACILITIES COUNCILST/P000525/1