Beschreibung
The Lyman-alpha forest is a powerful cosmological probe of matter density fluctuations in the weakly non-linear regime through the high redshift and underdense intergalactic medium (IGM). On small scales, the Lyman-alpha 1D flux power spectrum is uniquely sensitive to both the properties of dark matter and the complex gas dynamics driven by IGM photoheating during reionization, offering cosmological constraints that are complementary to other probes, such as the CMB. In this talk, I present recent constraints on two dark matter candidates separated by more than 20 orders of magnitude in mass: Cold+Warm Dark Matter (CWDM) and axion-like particles (ALPs), derived by comparing the Sherwood-Relics hydrodynamical simulation suite with high signal-to-noise ratio, high-redshift UVES and HIRES spectra. These results highlight how small-scale features in the forest reveal fundamental aspects of both dark matter and the IGM thermal history.