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Title: Studying the Ultraviolet Spectrum of the First Spectroscopically Confirmed Supernova at redshift two

Here, 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<1) and high redshift (z>1), but there is clear evidence of diversity in the spectrum at <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<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.
  1. Univ. of Southampton, Southampton (United Kingdom). et al.
Publication Date:
Report Number(s):
arXiv:1712.04535; FERMILAB-PUB-17-380-AE
Journal ID: ISSN 1538-4357; 1642976
Grant/Contract Number:
AC02-07CH11359; ST/N000688/1; 615929; AST-1311862; NAS 5-26555; AC05-00OR22725; NNX15AR41G; AST-1518052; AC02-05CH11231; AST-1138766; AST-1536171; AYA2015-71825; ESP2015-66861; FPA2015-68048; SEV-2016-0588; SEV-2016-0597; MDM-2015-0509; 240672; 291329; 306478
Accepted Manuscript
Journal Name:
The Astrophysical Journal (Online)
Additional Journal Information:
Journal Name: The Astrophysical Journal (Online); Journal Volume: 854; Journal Issue: 1; Journal ID: ISSN 1538-4357
Institute of Physics (IOP)
Research Org:
SLAC National Accelerator Lab., Menlo Park, CA (United States); Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25); National Science Foundation (NSF); TABASGO Foundation; Christopher R. Redlich Fund; National Aeronautic and Space Administration (NASA); USDOE Office of Science (SC), Advanced Scientific Computing Research (ASCR) (SC-21); European Union (EU); National Research Council (NRC); Miller Institute for Basic Research in Science (U.C. Berkeley); Gordon & Betty Moore Foundation; Alfred P. Sloan Foundation; David and Lucile Packard Foundation
Contributing Orgs:
DES; The DES Collaboration
Country of Publication:
United States
79 ASTRONOMY AND ASTROPHYSICS; supernovae: general; supernovae: individual (DES16C2nm); surveys; distance scale
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1418144; OSTI ID: 1432248