Seven Years of SN 2014C: a Multi-Wavelength Synthesis of an Extraordinary Supernova

Abstract

SN 2014C was originally classified as a Type Ib supernova, but at phase ϕ = 127 d post-explosion strong Hα emission was observed. SN 2014C has since been observed in radio, infrared, optical and X-ray bands. Here we present new optical spectroscopic and photometric data spanning ϕ = 947 - 2494 d post-explosion. We address the evolution of the broadened Hα emission line, as well as broad [O III] emission and other lines. We also conduct a parallel analysis of all publicly available multi-wavelength data. From our spectra, we find a nearly constant Hα FWHM velocity width of {\sim}2000 km/s that is significantly lower than that of other broadened atomic transitions ({\sim}3000 - 7000 km/s) present in our spectra ([O I] λ6300; [O III] λλ4959,5007; He I λ7065; [Ca II] λλ7291,7324). The late radio data demand a fast forward shock ({\sim}10,000 km/s at ϕ = 1700 d) in rarified matter that contrasts with the modest velocity of the Hα. We propose that the infrared flux originates from a toroidal-like structure of hydrogen surrounding the progenitor system, while later emission at other wavelengths (radio, X-ray) likely originates predominantly from the reverse shock in the ejecta and the forward shock in the quasi-spherical progenitor He wind. We propose that the Hα emission arises in the boundary layer between the ejecta and torus. We also consider the possible roles of a pulsar and a binary companion.

33 pages, 12 figures

References in corpus (11)

• PTF11iqb: Cool supergiant mass loss that bridges the gap between Type IIn and normal supernovae
• Analysis of Late--time Light Curves of Type IIb, Ib and Ic Supernovae
• The very young resolved stellar populations around stripped-envelope supernovae
• X-ray Emission from SN 2012ca: A Type Ia-CSM Supernova Explosion in a Dense Surrounding Medium
• The peculiar mass-loss history of SN 2014C as revealed through AMI radio observations
• Supernova ejecta interacting with a circumstellar disk. I. two-dimensional radiation-hydrodynamic simulations
• X-Ray and Radio Emission from the Luminous Supernova 2005kd
• Searching for the expelled hydrogen envelope in Type I supernovae via late-time H-alpha emission
• The Exceptional X-ray Evolution of SN1996cr in High Resolution
• SN 2014C: VLBI image shows a shell structure and decelerated expansion
• Outside the Wall: Hydrodynamics of Type I Supernovae Interacting with a Partially Swept-Up Circumstellar Medium

Cited by in corpus (1)

• Resurrection of type IIL supernova 2018ivc: Implications for a binary evolution sequence connecting hydrogen-rich and -poor progenitors