The paper describes techniques for incorporating feedback from star formation and black hole accretion into simulations of isolated and merging galaxies. Due to the current limitations in computational power, detailed resolutions are not feasible on galactic scales. The authors propose a coarse-grained approach to model the properties of the interstellar medium and black hole accretion, allowing these effects to be included on resolved scales. They use a multiphase description of star-forming gas, where feedback from star formation pressurizes highly overdense gas, altering its effective equation of state. This allows for the construction of stable galaxy models with larger gas fractions compared to previous numerical work. The model also includes gas accretion onto central supermassive black holes, with feedback regulating black hole growth. In gas-rich mergers, the interplay between starbursts and central AGN activity is observed, leading to powerful quasar-driven winds once the black hole reaches a critical size. The simulation methodology addresses the coupled processes of gas dynamics, star formation, and black hole accretion during galaxy formation.The paper describes techniques for incorporating feedback from star formation and black hole accretion into simulations of isolated and merging galaxies. Due to the current limitations in computational power, detailed resolutions are not feasible on galactic scales. The authors propose a coarse-grained approach to model the properties of the interstellar medium and black hole accretion, allowing these effects to be included on resolved scales. They use a multiphase description of star-forming gas, where feedback from star formation pressurizes highly overdense gas, altering its effective equation of state. This allows for the construction of stable galaxy models with larger gas fractions compared to previous numerical work. The model also includes gas accretion onto central supermassive black holes, with feedback regulating black hole growth. In gas-rich mergers, the interplay between starbursts and central AGN activity is observed, leading to powerful quasar-driven winds once the black hole reaches a critical size. The simulation methodology addresses the coupled processes of gas dynamics, star formation, and black hole accretion during galaxy formation.