2016/11/30 by M. Nicholl, E. Berger, R. Margutti +5 · 78 citations
Earth and Planetary Sciences · Physics and Astronomy · #Absorption (acoustics) #Astrophysics and Cosmic Phenomena #Earth Systems and Cosmic Evolution #Gamma-ray bursts and supernovae #Light curve #Magnetar #Opacity #Spectral line #Supernova #Ultraviolet #Wavelength #astro-ph.CO #astro-ph.HE #astro-ph.SR
paper · pdf · doi:10.3847/2041-8213/aa56c5
published in The Astrophysical Journal Letters 835(1), L8 (IOP Publishing) · Updated to match accepted version (ApJL)
openalex created_date 2016/11/30 · openalex publication_date 2017/01/17 · arxiv created 2017/01/20 · arxiv updated 2017/01/23 · openalex updated_date 2026/08/05
Abstract Since the discovery of superluminous supernovae (SLSNe) in the last decade, it has been known that these events exhibit bluer spectral energy distributions than other supernova subtypes, with significant output in the ultraviolet. However, the event Gaia16apd seems to outshine even the other SLSNe at rest-frame wavelengths below ∼3000 Å. Yan et al. have recently presented HST UV spectra and attributed the UV flux to low iron-group abundance in the outer ejecta, and hence reduced line blanketing. Here, we present UV and optical light curves over a longer baseline in time, revealing a rapid decline at UV wavelengths despite a typical optical evolution. Combining the published UV spectra with our own optical data, we demonstrate that Gaia16apd has a much hotter continuum than virtually any SLSN at maximum light, but it cools rapidly thereafter and is indistinguishable from the others by ∼10–15 days after peak. Comparing the equivalent widths of UV absorption lines with those of other events, we show that the excess UV continuum is a result of a more powerful central power source, rather than a lack of UV absorption relative to other SLSNe or an additional component from interaction with the surrounding medium. These findings strongly support the central-engine hypothesis for hydrogen-poor SLSNe. An explosion ejecting M ej = 4.8(0.2/ κ ) M ⊙ , where κ is the opacity in cm 2 g −1 , and forming a magnetar with spin period P = 2 ms, and B = 2 × 10 14 G (lower than other SLSNe with comparable rise times) can consistently explain the light curve evolution and high temperature at peak. The host metallicity, Z = 0.18 Z ⊙ , is comparable to other SLSNe.