2018/07/20 by Kornpob Bhirombhakdi, R. Chornock, Ryan Chornock +6
Physics and Astronomy · #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Black-body radiation #Ejecta #Emission spectrum #Gamma-ray bursts and supernovae #Light curve #Magnetar #Neutron star #Optics #Photometry (optics) #Photosphere #Physics #Pulsars and Gravitational Waves Research #RADIUS #Radiation #Spectral line #Stars #Supernova #astro-ph.HE
paper · pdf · doi:10.1093/mnras/stz1928
arxiv created 2018/07/20 · openalex publication_date 2019/07/24 · arxiv updated 2019/07/31 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
ABSTRACT SN 2008es is one of the rare cases of a Type II superluminous supernova (SLSN), showing no narrow features in its early-time spectra, and therefore, its powering mechanism is under debate between circumstellar interaction (CSI) and magnetar spin-down. Late-time data are required for better constraints. We present optical and near-infrared (NIR) photometry obtained from Gemini, Keck, and Palomar Observatories from 192 to 554 d after explosion. Only broad H α emission is detected in a Gemini spectrum at 288 d. The line profile exhibits red-wing attenuation relative to the early-time spectrum. In addition to the cooling SN photosphere, an NIR excess with blackbody temperature ∼1500 K and radius ∼1016 cm is observed. This evidence supports dust condensation in the cool dense shell being responsible for the spectral evolution and NIR excess. We favour CSI, with ∼2–3 M⊙ of circumstellar material (CSM) and ∼10–20 M⊙ of ejecta, as the powering mechanism, which still dominates at our late-time epochs. Both models of uniform density and steady wind fit the data equally well, with an effective CSM radius ∼1015 cm, supporting the efficient conversion of shock energy to radiation by CSI. A low amount (≲0.4 M⊙) of 56Ni is possible but cannot be verified yet, since the light curve is dominated by CSI. The magnetar spin-down powering mechanism cannot be ruled out, but is less favoured because it overpredicts the late-time fluxes and may be inconsistent with the presence of dust.