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

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posted on 2023-06-09, 12:22 authored by M Smith, M Sullivan, R C Nichol, L Galbany, C B D'Andrea, C Inserra, C Lidman, A Rest, M Schirmer, A V Filippenko, W Zheng, S Bradley Cenko, C R Angus, P J Brown, T M Davis, D A Finley, R J Foley, S González-Gaitán, C P Gutiérrez, R Kessler, S Kuhlmann, J Marriner, A Möller, P E Nugent, S Prajs, R Thomas, R Wolf, Kathy RomerKathy Romer, A Zenteno, and others, The DES Collaboration
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.

Funding

University of Sussex Astronomy Consolidated Grant 2017-2020; G2050; STFC-SCIENCE AND TECHNOLOGY FACILITIES COUNCIL; ST/P000525/1

History

Publication status

  • Published

File Version

  • Published version

Journal

Astrophysical Journal

ISSN

0004-637X

Publisher

American Astronomical Society

Issue

37

Volume

854

Page range

1-14

Department affiliated with

  • Physics and Astronomy Publications

Full text available

  • Yes

Peer reviewed?

  • Yes

Legacy Posted Date

2018-03-05

First Open Access (FOA) Date

2018-03-05

First Compliant Deposit (FCD) Date

2018-03-05

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