Studying the Ultraviolet Spectrum of the First Spectroscopically Confirmed Supernova at redshift two
Creators: name: Smith, M.
name: Sullivan, M.
name: Nichol, R. C.
name: Galbany, L.
name: D'Andrea, C. B.
name: Inserra, C.
name: Lidman, C.
name: Rest, A.
name: Schirmer, M.
name: Filippenko, A. V.
name: Zheng, W.
name: Cenko, S. Bradley
name: Angus, C. R.
name: Brown, P. J.
name: Davis, T. M.
name: Finley, D. A.
name: Gonzalez-Gaitan, S.
name: Gutierrez, C. P.
name: Kessler, R.
name: Kuhlmann, S.
name: Marriner, J.
name: Moller, A.
name: Nugent, P. E.
name: Prajs, S.
name: Thomas, R.
name: Wolf, R.
name: Zenteno, A.
name: Abbott, T. M. C.
name: Abdalla, F. B.
name: Allam, S.
name: Annis, J.
name: Bechtol, K.
name: Benoit-Levy, A.
name: Bertin, E.
name: Brooks, D.
name: Burke, D. L.
name: Rosell, A. Carnero
name: Kind, M. Carrasco
name: Carretero, J.
name: Castander, F. J.
name: Crocce, M.
name: Cunha, C. E.
name: da Costa, L. N.
name: Davis, C.
name: Desai, S.
name: Diehl, H. T.
name: Doel, P.
name: Eifler, T. F.
name: Flaugher, B.
name: Fosalba, P.
name: Frieman, J.
name: Garcia-Bellido, J.
name: Gaztanaga, E.
name: Gerdes, D. W.
name: Goldstein, D. A.
name: Gruen, D.
name: Gruendl, R. A.
name: Gschwend, J.
name: Gutierrez, G.
name: Honscheid, K.
name: James, D. J.
name: Johnson, M. W. G.
name: Kuehn, K.
name: Kuropatkin, N.
name: Li, T. S.
name: Lima, M.
name: Maia, M. A. G.
name: Marshall, J. L.
name: Martini, P.
name: Menanteau, F.
name: Miller, C. J.
name: Miguel, R.
name: Ogando, R. L. C.
name: Petravick, D.
name: Plazas, A. A.
name: Romer, A. K.
name: Rykoff, E. S.
name: Sako, M.
name: Sanchez, E.
name: Scarpine, V.
name: Schindler, R.
name: Schubnell, M.
name: Sevilla-Noarbe, I.
name: Smith, R. C.
name: Soares-Santos, M.
name: Sobreira, F.
name: Suchyta, E.
name: Swanson, M. E. C.
name: Tarle, G.
name: Walker, A. R.
Publisher: name: arXiv
Year: 2017
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: Astrophysics of Galaxies (astro-ph.GA)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: 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$\pm$0.06. The high redshift of DES16C2nm provides a unique opportunity to study the ultraviolet (UV) properties of SLSNe-I. Combining DES16C2nm with ten similar events from the literature, we show that there exists a homogeneous class of SLSNe-I in the UV (~2500A), 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&lt;1) and high redshift (z&gt;1), but there is clear evidence of diversity in the spectrum at &lt;2000A, 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&lt;1), we highlight that at z&gt;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.
description: Accepted for publication in ApJ