Systematic investigation of the fallback accretion powered model for hydrogen-poor superluminous supernovae

TL;DR

This study evaluates fallback accretion as a power source for hydrogen-poor superluminous supernovae, finding it can fit light curves but often requires unrealistic accretion masses unless efficiency is higher.

Contribution

It systematically tests the fallback accretion model using Bayesian light-curve fitting, revealing limitations in the required accreted mass for most supernovae.

Findings

Fallback accretion can produce good light-curve fits.

Most supernovae require implausibly large accreted masses.

Efficiency assumptions critically impact model viability.

Abstract

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.