Stirring the cosmic pot: how black hole feedback shapes the matter power spectrum in the FABLE simulations

Understanding the impact of baryonic physics on cosmic structure formation is crucial for accurate cosmological predictions, especially as we usher in the era of large galaxy surv e ys with the Rubin Observatory as well as the Euclid and Roman Space Telescopes. A key process that can redistribute matter across a large range of scales is feedback from accreting supermassive black holes. How exactly these active galactic nuclei (AGNs) operate from sub-parsec to Mega-parsec scales ho we ver remains largely unknown. To understand this, we investigate how different AGN feedback models in the FABLE simulation suite affect the cosmic evolution of the matter power spectrum (MPS). Our analysis reveals that AGN feedback significantly suppresses clustering at scales k ∼10 h cMpc ^-1, with the strongest effect at redshift z = 0 causing a reduction of ∼10 per cent with respect to the dark matter-only simulation. This is due to the efficient feedback in both radio (low Eddington ratio) and quasar (high Eddington ratio) modes in our fiducial FABLE model. We find that variations of the quasar and radio mode feedback with respect to the fiducial FABLE model have distinct effects on the MPS redshift evolution, with radio mode being more ef fecti ve on larger scales and later epochs. Furthermore, MPS suppression is dominated by AGN feedback effects inside haloes at z = 0, while for z ≳ 1 the matter distribution both inside and outside of haloes shapes the MPS suppression. Hence, future observations probing earlier cosmic times beyond z ∼1 will be instrumental in constraining the nature of AGN feedback.