Abstract
We present numerical simulations that include 1-D Eulerian multi-group radiation-hydrodynamics, 1-D non-LTE radiative transfer, and 2-D polarised radiative transfer for super-luminous interacting supernovae (SNe). Our reference model is a ~10Msun inner shell with 10^51erg ramming into a ~3Msun cold outer shell (the circumstellar-medium, or CSM) that extends from 10^15cm to 2x10^16cm and moves at 100km/s. We discuss the light curve evolution, which cannot be captured adequately with a grey approach. In these interactions, the shock-crossing time through the optically-thick CSM is much longer than the photon diffusion time. Radiation is thus continuously leaking from the shock through the CSM, in disagreement with the shell-shocked model that is often invoked. Our spectra redden with time, with a peak distribution in the near-UV during the first month gradually shifting to the optical range over the following year. Initially Balmer lines exhibit a narrow line core and the broad line wings that are characteristic of electron scattering in the SNe IIn atmospheres (CSM). At later times they also exhibit a broad blue shifted component which arises from the cold dense shell. Our model results are broadly consistent with the bolometric light curve and spectral evolution observed for SN2010jl. Invoking a prolate pole-to-equator density ratio in the CSM, we can also reproduce the ~2% continuum polarisation, and line depolarisation, observed in SN2010jl. By varying the inner shell kinetic energy and the mass and extent of the outer shell, a large range of peak luminosities and durations, broadly compatible with super-luminous SNe IIn like 2010jl or 2006gy, can be produced.
Highlights
Since the original identification of interacting supernovae (SNe; Dopita et al 1984; Niemela et al 1985) and the creation of the SN IIn class (Schlegel 1990), the sample of such peculiar Type II SNe has grown from a few to a few tens of events
We have presented numerical simulations for interacting SNe in which both the kinetic energy of the explosivelyproduced inner shell and the mass of the wind-produced outer shell are very large
Our contribution is novel because we post-process our multigroup radiation-hydrodynamics simulations with radiative transfer tools, to compute non-LTE spectra and polarisation signatures
Summary
Since the original identification of interacting supernovae (SNe; Dopita et al 1984; Niemela et al 1985) and the creation of the SN IIn class (Schlegel 1990), the sample of such peculiar Type II SNe has grown from a few to a few tens of events It has revealed an intriguing diversity, spanning a range of luminosities, duration, line profile morphology, with events like SNe 1988Z (Stathakis & Sadler 1991; Turatto et al 1993), 1994W (Sollerman et al 1998; Chugai et al 2004), 2006gy (Smith et al 2007), and the enigmatic SN 2009ip (Mauerhan et al 2013; Pastorello et al 2013; Margutti et al 2014). The radiative transfer modelling for SNe IIn comes at present in two flavours It is either based on the results of radiation hydrodynamics simulations but limited to a single line, e.g., Hα (Chugai et al 2004), or based on an ad-hoc atmospheric structure and the assumption of steady-state radiation through a diffusive optically thick inner boundary (Dessart et al 2009).
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