The Canada-France Imaging Survey: First results from the u-band component

TL;DR

The CFIS-u survey provides new high-quality u-band imaging data of the northern sky, revealing the structure and composition of the Galactic anticenter and enabling diverse astrophysical studies.

Contribution

This paper presents the first results from the CFIS-u component, including observational strategy and initial findings on Galactic structure and potential for future research.

Findings

Galactic anticenter structure extends beyond 20 kpc with similar metallicity to outer disk.

The structure is likely a buckled disk of old, metal-rich stars.

CFIS-u has potential for discovering dwarf galaxies and studying low-surface brightness features.

Abstract

The Canada-France Imaging Survey (CFIS) will map the northern high Galactic latitude sky in the $u$-band ("CFIS-u", 10,000$\, {\rm deg^2}$) and in the $r$-band ("CFIS-r", 5,000$\, {\rm deg^2}$), enabling a host of stand-alone science investigations, and providing some of the ground-based data necessary for photometric redshift determination for the Euclid mission. In this first contribution we present the $u$-band component of the survey, describe the observational strategy, and discuss some first highlight results, based on approximately one third of the final area. We show that the Galactic anticenter structure is distributed continuously along the line of sight, out to beyond 20 kpc, and possesses a metallicity distribution that is essentially identical to that of the outer disk sampled by APOGEE. This suggests that it is probably a buckled disk of old metal-rich stars, rather than a stream or a flare. We also discuss the future potential for CFIS-u in discovering star-forming dwarf galaxies around the Local Group, the characterization of the white dwarf and blue straggler population of the Milky Way, as well as its sensitivity to low-surface brightness structures in external galaxies.