Gravitation and Cosmology “Gravitation and Cosmology” group, coordinated by Nihan Katırcı, investigates fundamental questions about the nature of gravity, the dynamics of the universe, and the underlying principles governing cosmic evolution. Research topics include modifications of general relativity, dark energy and dark matter models, observational cosmology, cosmic tensions, and the interplay between theoretical models and astronomical data. The team combines analytical, numerical, and observational approaches to advance our understanding of the cosmos.Our group conducts advanced research in theoretical and observational cosmology, with a strong focus on gravitational physics and alternative theories of gravity. We explore fundamental questions about the universe, including the nature of gravity, cosmic expansion, dark energy, and dark matter, as well as testing extensions and alternatives to the standard LCDM model.A major part of our work involves addressing cosmological tensions by combining theoretical modeling with the latest observational datasets. We employ Python-based tools, Bayesian statistics, and Markov Chain Monte Carlo (MCMC) algorithms for parameter estimation, model comparison, and data analysis. Our research spans both standard and modified cosmological models, aiming to probe physics beyond general relativity and the Standard Model.The group actively participates in international collaborations, including the CosmoVerse COST Action, contributing to working groups on Fundamental Physics and Data Analysis in Cosmology, Cosmología Relativista y Gravitación funded by the Spanish Ministry of Science. Nationally, we engage with national and international universities and research centers promoting interdisciplinary collaborations with computer and software engineering departments to strengthen advanced data analysis capabilities.Our long-term goal is to establish an Observational Cosmology Group in Türkiye as well, building national capacity for independent, high-quality analysis of cosmological and astrophysical data, while training the next generation of scientists.