beecee Posted February 20, 2018 Posted February 20, 2018 Astronomers reveal secrets of most distant supernova ever detected February 20, 2018, University of Portsmouth Supernova. Credit: NASA An international team of astronomers, including Professor Bob Nichol from the University of Portsmouth, has confirmed the discovery of the most distant supernova ever detected – a huge cosmic explosion that took place 10.5 billion years ago, or three-quarters the age of the Universe itself. The exploding star, named DES16C2nm, was detected by the Dark Energy Survey (DES), an international collaboration to map several hundred million galaxies in order to find out more about dark energy – the mysterious force believed to be causing the accelerated expansion of the Universe. Read more at: https://phys.org/news/2018-02-astronomers-reveal-secrets-distant-supernova.html#jCp the paper: http://iopscience.iop.org/article/10.3847/1538-4357/aaa126/meta Studying the Ultraviolet Spectrum of the First Spectroscopically Confirmed Supernova at Redshift Two Abstract We present observations of DES16C2nm, the first spectroscopically confirmed hydrogen-free superluminous supernova (SLSN-I) at redshift . 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 . 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 ( 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 () and high redshift (), but there is clear evidence of diversity in the spectrum at , 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 (), we highlight that at 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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