# Extremely late photometry of SN~2011fe

## TL;DR

This study analyzes extremely late-time photometry of SN 2011fe to test supernova explosion models, but finds that physical uncertainties hinder definitive model discrimination at these epochs.

## Contribution

It provides the first detailed analysis of supernova SN 2011fe's photometry between 900 and 1600 days post-explosion, highlighting the challenges in using late-time light curves for model discrimination.

## Key findings

- Late-time light curves are affected by poorly constrained physical processes.
- Isotopic abundance measurements at late epochs have large systematic uncertainties.
- Current data cannot reliably exclude supernova explosion models.

## Abstract

Type Ia supernovae are widely accepted to be the outcomes of thermonuclear explosions in white dwarf stars. However, many details of these explosions remain uncertain (e.g. the mass, ignition mechanism, and flame speed). Theory predicts that at very late times (beyond 1000 d) it might be possible to distinguish between explosion models. Few very nearby supernovae can be observed that long after the explosion. The Type Ia supernova SN 2011fe located in M101 and along a line of sight with negligible extinction, provides us with the once-in-a-lifetime chance to obtain measurements that may distinguish between theoretical models. In this work, we present the analysis of photometric data of SN 2011fe taken between 900 and 1600 days after explosion with Gemini and HST. At these extremely late epochs theory suggests that the light curve shape might be used to measure isotopic abundances which is a useful model discriminant. However, we show in this work that there are several currently not well constrained physical processes introducing large systematic uncertainties to the isotopic abundance measurement. We conclude that without further detailed knowledge of the physical processes at this late stage one cannot reliably exclude any models on the basis of this dataset.