CFIS is a Legacy survey that will answer some of the most fundamental questions in astronomy, about the properties of dark matter and dark energy, the growth of structure in the Universe from Galactic to cluster scales, and the assembly of the Milky-Way. These ambitious goals are achievable only with homogeneous, multiwavelength data covering large areas of the sky. CFIS exploits the unparalleled u-band sensitivity, excellent r-band performance and recovered image quality (IQ) of CFHT through two related components, enabling discoveries about structure formation from the Milky Way to high redshifts. Both survey components probe structure formation on different scales, and the legacy value of CFIS includes its essential contribution to existing and future deep, wide-field northern surveys by leveraging the premier capabilities of CFHT. CFIS represents a critical component of the data needed for photometric redshifts in the Euclid space mission, and thus enables a Stage IV measurement of dark energy properties. It is however designed specifically to complement the existing PS1 imaging and SDSS spectroscopic surveys to enable autonomous science, and is naturally synergistic to many other surveys. This deliberate complementarity enables countless investigations.
To understand the role of the environment on galaxy evolution, we propose a deep Halpha imaging survey of the Virgo cluster over ~200deg2. VESTIGE will be the first deep blind Halpha survey of a nearby cluster. The data will be perfectly suited for comparison with hydrodynamic simulations of gas stripping in dense environments, now able to reach resolutions similar to those of the multifrequency data available for Virgo. The combination of data and simulations will allow us to address a wide range of astrophysical questions: the star formation process in galaxies, the fate of the stripped gas in clusters, the dynamical structure of the nearest galaxy cluster, extragalactic planetary nebulae and the origin of the diffuse intracluster light, the ionised gas emission in the Milky Way, and the star formation activity of high-z line emitters. Not only will VESTIGE be the definitive study of the perturbing mechanisms in high-density regions for years to come, but it will yield the benchmark observational database against which the next generation of cosmological models will be tested. CFHT's narrow-band imaging capability is unique in its class for years to come. As such, VESTIGE will be a lasting legacy of CFHT
Major gains in substellar astrophysics have been achieved thanks to investment in large sky surveys, dedicated photometric and spectroscopic followup, and advances in theoretical efforts. New brown dwarf discoveries now probe extremes of temperature, gravity, and age, extending into the planetary-mass regime and deepening the connection between brown dwarfs and directly imaged exoplanets. The empirical foundation of these studies are accurate distance measurements via trigonometric parallaxes, yet such faint objects are inaccessible to astrometry in the optical (e.g., Gaia). We propose a 3-year Large Program using WIRCam to obtain high-precision infrared astrometry of these objects, in order to measure their fundamental parameters and to robustly test theoretical models of substellar evolution and ultracool atmospheres. This program leverages our expertise, methods, and observations from the long-running WIRCam parallax program conducted by UH.