Outskirts of spiral galaxies: result of a secular evolution process?

TL;DR

This study investigates the evolution of stellar disk truncations in spiral galaxies over the last 8 billion years, revealing inside-out growth and secular processes shaping galaxy outskirts.

Contribution

It provides observational evidence of the evolution of disk break positions and color gradients, supporting secular evolution models for galaxy disk formation.

Findings

The break radius has increased by a factor of 1.3+/-0.1 since z~1.

Radial color profiles show inside-out bluing and reddening beyond the break.

Results support models where stars form inside the break and migrate outward through secular processes.

Abstract

We present our recent results on the properties of the outskirts of disk galaxies. In particular, we focus on spiral galaxies with stellar disk truncations in their radial surface brightness profiles. Using SDSS, UDF and GOODS data we show how the position of the break (i.e., a direct estimator of the size of the stellar disk) evolves with time since z~1. Our findings agree with an evolution on the radial position of the break by a factor of 1.3+/-0.1 in the last 8 Gyr for galaxies with similar stellar masses. We also present radial color gradients and how they evolve with time. At all redshift we find a radial inside-out bluing reaching a minimum at the position of the break radius, this minimum is followed by a reddening outwards. Our results constrain several galaxy disk formation models and favour a scenario where stars are formed inside the break radius and are relocated in the outskirts of galaxies through secular processes.