109 research outputs found
The magnetar model for Type I superluminous supernovae I: Bayesian analysis of the full multicolour light curve sample with MOSFiT
We use the new Modular Open Source Fitter for Transients (MOSFiT) to model 38
hydrogen-poor superluminous supernovae (SLSNe). We fit their multicolour light
curves with a magnetar spin-down model and present the posterior distributions
of magnetar and ejecta parameters. The colour evolution can be well matched
with a simple absorbed blackbody. We find the following medians (1
ranges): spin period 2.4 ms (1.2-4 ms); magnetic field G
(0.2-1.8 G); ejecta mass 4.8 Msun (2.2-12.9 Msun); kinetic
energy erg (1.9-9.8 erg). This
significantly narrows the parameter space compared to our priors, showing that
although the model is flexible, the parameter space relevant to SLSNe is well
constrained by existing data. The requirement that the instantaneous engine
power is erg at the light curve peak necessitates either a large
rotational energy (P<2 ms), or more commonly that the spin-down and diffusion
timescales be well-matched. We find no evidence for separate populations of
fast- and slow-declining SLSNe, which instead form a continuum both in light
curve widths and inferred parameters. Variations in the spectra are well
explained through differences in spin-down power and photospheric radii at
maximum-light. We find no correlations between any model parameters and the
properties of SLSN host galaxies. Comparing our posteriors to stellar evolution
models, we show that SLSNe require rapidly rotating (fastest 10%) massive stars
(> 20 Msun), and that this is consistent with the observed SLSN rate. High
mass, low metallicity, and likely binary interaction all serve to maintain
rapid rotation essential for magnetar formation. By reproducing the full set of
SLSN light curves, our posteriors can be used to inform photometric searches
for SLSNe in future survey data
Systematic investigation of the fallback accretion powered model for hydrogen-poor superluminous supernovae
The energy liberated by fallback accretion has been suggested as a possible
engine to power hydrogen-poor superluminous supernovae. We systematically
investigate this model using the Bayesian light-curve fitting code MOSFiT
(Modular Open Source Fitter for Transients), fitting the light curves of 37
hydrogen-poor superluminous supernovae assuming a fallback accretion central
engine. We find that this model can yield good fits to their light curves, with
a fit quality that rivals the popular magnetar engine models. Examining our
derived parameters for the fallback model, we find the total energy
requirements from the accretion disk are estimated to be 0.002 - 0.7 Msun c^2.
If we adopt a typical conversion efficiency ~ 1e-3, the required mass to
accrete is thus 2 - 700 Msun. Many superluminous supernovae, therefore, require
an unrealistic accretion mass, and so only a fraction of these events could be
powered by fallback accretion unless the true efficiency is much greater than
our fiducial value. The superluminous supernovae that require the smallest
amounts of fallback mass still remain to be the fallback accretion powered
supernova candidates, but they are difficult to be distinguished solely by
their light curve properties.Comment: 12 pages, 8 figures, 3 tables, accepted by The Astrophysical Journa
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