Abstract:
Numerous superluminous supernovae (SLSNe) of Type Ic have been discovered and monitored in the last decade. The favored mechanism at their origin is a sustained power injection from a magnetar. This study presents non-local thermodynamic equilibrium (nLTE) time-dependent radiative transfer simulations of various single carbon-rich Wolf-Rayet star explosions influenced by magnetars of diverse properties and covering from a few days to one or two years after explosion. Nonthermal processes are treated; the magnetar-power deposition profile is prescribed; dynamical effects are ignored. In this context, the main influence of the magnetar power is to boost the internal energy of the ejecta on week-long time scales, enhancing the ejecta temperature and ionization, shifting the spectral energy distribution to the near-UV (even for the adopted solar metallicity), creating blue optical colors. Varying the ejecta and magnetar properties introduces various stretches and shifts to the light curve (rise time, peak or nebular luminosity, light curve width). At maximum, all models show the presence of OII and CII lines in the optical, and more rarely OIII and CIII lines. Non-thermal effects are found to be negligible during the high-brightness phase. After maximum, higher energy explosions are hotter and more ionized, and produce spectra that are optically bluer. Clumping is a source of spectral diversity after maximum. Clumping is essential to trigger ejecta recombination and yield the presence of OI, CaII, and FeII lines from a few weeks after maximum until nebular times. The UV and optical spectrum of Gaia16apd at maximum or the nebular spectrum of LSQ14an at +410d are compatible with some models that assume no clumping. However, most observed SLSNe Ic seem to require clumping from early post-maximum to nebular times (e.g., SN2007bi at +46 and +367d; Gaia16apd at +43d).

The full paper is available here

To access the spectra for some of these models, click on the following links (each zipped tar file contains the multi-epoch spectra and a list relating model index to the time since explosion):

5p11Bx2.tgz
5p11Bx2nt.tgz
r0e1.tgz
r0e2.tgz
r0e2s.tgz
r0e4.tgz
r0e2ep.tgz
r0e2ep3cl.tgz
r0e1ep3.tgz
r0e2ep3.tgz
r0e2bm.tgz
r0e2cl.tgz
r0e2ep2.tgz
r0e2ep3.tgz