One thousand days of SN 2015bn: HST imaging shows a light curve flattening consistent with magnetar predictions

Abstract

We present the first observations of a Type I superluminous supernova (SLSN) at $\gtrsim 1000$ days after maximum light. We observed SN 2015bn using the Hubble Space Telescope Advanced Camera for Surveys in the F475W, F625W and F775W filters at 721 days and 1068 days. SN 2015bn is clearly detected and resolved from its compact host, allowing reliable photometry. A galaxy template constructed from these data further enables us to isolate the SLSN flux in deep ground-based imaging. We measure a light curve decline rate at $>700$ days of $0.19\pm 0.03$ mag (100 d)${}^{-1}$, much shallower than the earlier evolution, and slower than previous SLSNe (at any phase) or the decay rate of ${}^{56}$Co. Neither additional radioactive isotopes nor a light echo can consistently account for the slow decline. A spectrum at 1083 days shows the same [O I] and [Ca II] lines as seen at $\sim 300-400$ days, with no new features to indicate strong circumstellar interaction. Radio limits with the Very Large Array rule out an extended wind for mass-loss rates $10^{-2.7}\lesssim \dot{M}/v_{10}\lesssim 10^{-1.1}$ M${}_{\odot }$ yr${}^{-1}$ (where $v_{10}$ is the wind velocity in units of 10 km s${}^{-1}$). The optical light curve is consistent with $L\propto t^{-4}$, which we show is expected for magnetar spin-down with inefficient trapping; furthermore, the evolution matches predictions from earlier magnetar model fits. The opacity to magnetar radiation is constrained at $\sim 0.01$ cm${}^2$ g${}^{-1}$, consistent with photon-matter pair-production over a broad $\sim$GeV-TeV range. This suggests the magnetar spectral energy distribution, and hence the 'missing energy' leaking from the ejecta, may peak in this range.

arXiv commentAccepted for publication in ApJL, updated to match accepted version

References in corpus (45)

• The Seventh Data Release of the Sloan Digital Sky Survey
• Detailed Structural Decomposition of Galaxy Images
• The Nucleosynthetic Signature of Population III
• Supernova Light Curves Powered by Young Magnetars
• Hydrogen-poor superluminous stellar explosions
• Supernova 2007bi as a pair-instability explosion
• The First Systematic Study of Type Ibc Supernova Multi-band Light Curves
• Super Luminous Ic Supernovae: catching a magnetar by the tail
• An Open Catalog for Supernova Data
• Slowly fading super-luminous supernovae that are not pair-instability explosions
• The magnetar model for Type I superluminous supernovae I: Bayesian analysis of the full multicolour light curve sample with MOSFiT
• MOSFiT: Modular Open-Source Fitter for Transients
• Super-luminous supernovae: 56Ni power versus magnetar radiation
• Pan-STARRS1 Discovery of Two Ultra-Luminous Supernovae at z ~ 0.9
• The Radio and X-ray Luminous SN 2003bg and the Circumstellar Density Variations Around Radio Supernovae
• SN 2015bn: a detailed multi-wavelength view of a nearby superluminous supernova
• Superluminous supernovae
• Ionization Break-Out from Millisecond Pulsar Wind Nebulae: an X-ray Probe of the Origin of Superluminous Supernovae
• Light curves of hydrogen-poor Superluminous Supernovae from the Palomar Transient Factory
• The Radio Evolution of the Ordinary Type Ic SN 2002ap
• Effects of Fall-Back Accretion on Proto-Magnetar Outflows in Gamma-Ray Bursts and Superluminous Supernovae
• Hydrogen-Poor Superluminous Supernovae from the Pan-STARRS1 Medium Deep Survey
• The host galaxy and late-time evolution of the Super-Luminous Supernova PTF12dam
• Hydrogen-poor Superluminous Supernovae With Late-time H-alpha Emission: Three Events From the Intermediate Palomar Transient Factory
• Superluminous supernova 2015bn in the nebular phase: evidence for the engine-powered explosion of a stripped massive star
• Superluminous Supernovae Powered by Magnetars: Late-time Light Curves and Hard Emission Leakage
• Complexity in the light curves and spectra of slow-evolving superluminous supernovae
• Unveiling the Engines of Fast Radio Bursts, Super-Luminous Supernovae, and Gamma-Ray Bursts
• SN 2012au: A Golden Link Between Superluminous Supernovae and Their Lower-Luminosity Counterparts
• Spectropolarimetry of superluminous supernovae: insight into their geometry
• The light curve of SN 1987A revisited: constraining production masses of radioactive nuclides
• PS1-14bj: A Hydrogen-Poor Superluminous Supernova With a Long Rise and Slow Decay
• The Double-Peaked SN2013ge: a Type Ib/c SN with an Asymmetric Mass Ejection or an Extended Progenitor Envelope
• Reconciling the infrared catastrophe and observations of SN 2011fe
• Direct evidence for a supernova interacting with a large amount of hydrogen-free circumstellar material
• Results from a systematic survey of X-ray emission from Hydrogen-poor Superluminous Supernovae
• Radio and X-rays From SN 2013df Enlighten Progenitors of Type IIb Supernovae
• The evolution of superluminous supernova LSQ14mo and its interacting host galaxy system
• Whimper of a Bang: Documenting the Final Days of the Nearby Type Ia Supernova 2011fe
• Time-resolved polarimetry of the superluminous SN 2015bn with the Nordic Optical Telescope
• Extremely late photometry of SN~2011fe
• Observations of SN 2015F suggest a correlation between the intrinsic luminosity of Type Ia supernovae and the shape of their light curves >900 days after explosion
• Properties of magnetars mimicking 56Ni-powered light curves in Type Ic superluminous supernovae
• The Type I Superluminous Supernova PS16aqv: Lightcurve Complexity and Deep Limits on Radioactive Ejecta in a Fast Event
• Search for gamma-ray emission from super-luminous supernovae with the Fermi-LAT

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