Cosmological feedback from a halo assembly perspective

          @misc{ pirsa_PIRSA:25070006,
            doi = {10.48660/25070006},
            url = {https://pirsa.org/25070006},
            author = {Peiris, Hiranya},
            keywords = {Cosmology},
            language = {en},
            title = {Cosmological feedback from a halo assembly perspective},
            publisher = {Perimeter Institute},
            year = {2025},
            month = {jul},
            note = {PIRSA:25070006 see, \url{https://pirsa.org}}
          }
          

Abstract

The impact of feedback from galaxy formation on cosmological probes is typically quantified in terms of the suppression of the matter power spectrum in hydrodynamical compared to gravity-only simulations. In this paper, we instead study how baryonic feedback impacts halo assembly histories and thereby imprints on cosmological observables. We investigate the sensitivity of the thermal Sunyaev-Zel'dovich effect (tSZ) power spectrum, X-ray number counts, weak lensing and kinetic Sunyaev-Zel'dovich (kSZ) stacked profiles to halo populations as a function of mass and redshift. We then study the imprint of different feedback implementations in the FLAMINGO suite of cosmological simulations on the assembly histories of these halo populations, as a function of radial scale. We find that kSZ profiles target lower-mass halos (M200m∼10^13.1M⊙) compared to all other probes considered (M200m∼10^15M⊙). Feedback is inefficient in high-mass clusters with ∼10^15M⊙ at z=0, but was more efficient at earlier times in the same population, with a ∼5-10% effect on mass at 22). These findings are tied together by noting that, regardless of redshift, feedback most efficiently redistributes baryons when halos reach a mass of M200m≃10^12.8M⊙ and ceases to have any significant effect by the time M200m≃10^15M⊙. We put forward strategies for minimizing sensitivity of lensing analyses to baryonic feedback, and for exploring baryonic resolutions to the unexpectedly low tSZ power in cosmic microwave background observations.