# Stellar Disc Truncations and Extended Haloes in Face-on Spiral Galaxies

## TL;DR

This study uses deep imaging data to analyze faint structures in spiral galaxies, identifying stellar haloes and truncations, and examining their relationships with galaxy size and light scattering effects.

## Contribution

It provides new observational evidence of stellar haloes and truncations in face-on spiral galaxies, and explores their mutual exclusivity and scaling relations.

## Key findings

- Truncations found in 3 galaxies.
- Extended stellar haloes observed in 15 galaxies.
- Halo presence correlates with galaxy size and is mutually exclusive with truncations.

## Abstract

We use data from the IAC Stripe82 Legacy Project to study the surface photometry of 22 nearby, face-on to moderately inclined spiral galaxies. The reprocessed and combined Stripe 82 $g'$, $r'$ and $i'$ images allow us to probe the galaxy down to 29-30 $r'$-magnitudes/arcsec$^2$ and thus reach into the very faint outskirts of the galaxies. Truncations are found in three galaxies. An additional 15 galaxies are found to have an apparent extended stellar halo. Simulations show that the scattering of light from the inner galaxy by the Point Spread Function (PSF) can produce faint structures resembling haloes, but this effect is insufficient to fully explain the observed haloes. The presence of these haloes and of truncations is mutually exclusive, and we argue that the presence of a stellar halo and/or light scattered by the PSF can hide truncations. Furthermore, we find that the onset of the stellar halo and the truncations scales tightly with galaxy size. Interestingly, the fraction of light does not correlate with dynamic mass. Nineteen galaxies are found to have breaks in their profiles, the radius of which also correlates with galaxy size.