HEP-Astro Seminar | Galaxy-Galaxy Lensing and Lensing Ratios for Cosmological Analyses in the Dark Energy Survey

Galaxy cosmic surveys such as the Dark Energy Survey are a powerful tool to extract cosmological information. In particular, the combination of weak lensing and galaxy clustering measurements, usually known as 3x2pt, provides a potent and robust way to constrain the parameters controlling the structure formation in the late Universe. In this talk I will give an overview of the results and methods of Dark Energy Survey Y3 3x2pt cosmological analysis, focusing specially on the galaxy-galaxy lensing probe, which is the cross-correlation of the shapes of source background galaxies with lens foreground galaxy positions. I will also describe how we can construct suitable ratios of these galaxy-galaxy lensing measurements to exploit the otherwise usually disregarded small-scale information and naturally integrate it as part of the 3x2pt analysis. Finally, I will highlight some other galaxy-galaxy lensing applications, including learning about the galaxy-halo connection and low-surface brightness galaxies.