# Surviving companions of Type Ia supernovae: theory and observations

## TL;DR

This paper reviews the theoretical models and observational efforts to identify surviving companions of Type Ia supernovae, discussing current results and future prospects with advanced telescopes and astrometric data.

## Contribution

It provides a comprehensive overview of the theory and observations related to surviving companions of SNe Ia, highlighting new observational strategies and future research directions.

## Key findings

- Current searches have not definitively identified surviving companions.
- Upcoming telescopes like JWST and Gaia will enhance detection capabilities.
- The study outlines methods to characterize potential companion stars.

## Abstract

We review the theoretical background and the observational searches made for surviving companions of Type Ia supernovae (SNe Ia). Theory comprises the characteristics of the stellar binary companions of the exploding white dwarfs at the time of the supernova outburst and the expected effects on them of the explosion, as well as their subsequent evolution. That includes space velocities, rotation, luminosities (with discussion of possible mechanisms producing very faint companions) . We then present the searches already made in the Galactic remnants of Type Ia supernovae and we assess the results obtained up to now using ground--based telescopes and the {\it Hubble Space Telescope} ({\it HST}). The same is done for the remnants of this type in the Large Magellanic Cloud. We point to new SNRs of Type Ia that can be studied with groundbased telescopes,the {\it HST} and the {\it James Webb Space Telescope} ({\it JWST}), using various approaches such as characterization of peculiar stars through color--magnitude diagrams, determination of their stellar parameters by spectral fitting, and astrometric measurements. {\it Gaia} can provide, as well, useful astrometric information. Most of these approaches have been used in the SNe Ia remnants already explored. The future goal is to enlarge the sample to determine which stellar systems do actually produce these explosions.