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

  • Author(s): Smith, M
  • Sullivan, M
  • Nichol, RC
  • Galbany, L
  • D'Andrea, CB
  • Inserra, C
  • Lidman, C
  • Rest, A
  • Schirmer, M
  • Filippenko, AV
  • Zheng, W
  • Bradley Cenko, S
  • Angus, CR
  • Brown, PJ
  • Davis, TM
  • Finley, DA
  • Foley, RJ
  • González-Gaitán, S
  • Gutiérrez, CP
  • Kessler, R
  • Kuhlmann, S
  • Marriner, J
  • Möller, A
  • Nugent, PE
  • Prajs, S
  • Thomas, R
  • Wolf, R
  • Zenteno, A
  • Abbott, TMC
  • Abdalla, FB
  • Allam, S
  • Annis, J
  • Bechtol, K
  • Benoit-Lévy, A
  • Bertin, E
  • Brooks, D
  • Burke, DL
  • Carnero Rosell, A
  • Carrasco Kind, M
  • Carretero, J
  • Castander, FJ
  • Crocce, M
  • Cunha, CE
  • Da Costa, LN
  • Davis, C
  • Desai, S
  • Diehl, HT
  • Doel, P
  • Eifler, TF
  • Flaugher, B
  • Fosalba, P
  • Frieman, J
  • García-Bellido, J
  • Gaztanaga, E
  • Gerdes, DW
  • Goldstein, DA
  • Gruen, D
  • Gruendl, RA
  • Gschwend, J
  • Gutierrez, G
  • Honscheid, K
  • James, DJ
  • Johnson, MWG
  • Kuehn, K
  • Kuropatkin, N
  • Li, TS
  • Lima, M
  • Maia, MAG
  • Marshall, JL
  • Martini, P
  • Menanteau, F
  • Miller, CJ
  • Miquel, R
  • Ogando, RLC
  • Petravick, D
  • Plazas, AA
  • Romer, AK
  • Rykoff, ES
  • Sako, M
  • Sanchez, E
  • Scarpine, V
  • Schindler, R
  • Schubnell, M
  • Sevilla-Noarbe, I
  • Smith, RC
  • Soares-Santos, M
  • Sobreira, F
  • Suchyta, E
  • Swanson, MEC
  • Tarle, G
  • Walker, AR
  • et al.
Abstract

© 2018 The American Astronomical Society. All rights reserved. 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 (λrest ≊ 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 λrest < 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.

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