# Modeling the Light Curves of the Luminous Type Ic Supernova 2007D

## TL;DR

This study models the light curves of the luminous Type Ic supernova 2007D, suggesting a magnetar as the energy source rather than radioactive decay, and classifies it as a luminous transient bridging ordinary and superluminous supernovae.

## Contribution

It introduces multiband light curve modeling to determine the energy source of SN 2007D, challenging previous radioactive decay assumptions and proposing a magnetar-powered mechanism.

## Key findings

- Pure $^{56}$Ni model is disfavored.
- SN 2007D can be modeled by a magnetar with specific initial period and magnetic field.
- SN 2007D is likely a luminous transient bridging ordinary and superluminous supernovae.

## Abstract

SN~2007D is a nearby (redshift $z = 0.023146$), luminous Type Ic supernova (SN) having a narrow light curve (LC) and high peak luminosity. Previous research based on the assumption that it was powered by the $^{56}$Ni cascade decay suggested that the inferred $^{56}$Ni mass and the ejecta mass are $\sim 1.5$M$_{\odot}$ and $\sim 3.5$M$_{\odot}$, respectively. In this paper, we employ some multiband LC models to model the $R$-band LC and the color ($V-R$) evolution of SN~2007D to investigate the possible energy sources powering them. We find that the pure $^{56}$Ni model is disfavored; the multiband LCs of SN~2007D can be reproduced by a magnetar whose initial rotational period $P_{0}$ and magnetic field strength $B_p$ are $7.28_{-0.21}^{+0.21}$ (or $9.00_{-0.42}^{+0.32}$) ms and $3.10_{-0.35}^{+0.36}\times 10^{14}$ (or $2.81_{-0.44}^{+0.43}\times 10^{14}$) G, respectively. By comparing the spectrum of SN~2007D with that of some superluminous SNe (SLSNe), we find that it might be a luminous SN like several luminous ``gap-filler" optical transients that bridge ordinary and SLSNe, rather than a genuine SLSN.