ETHOS -- An effective parametrization and classification for structure formation: the non-linear regime at $z\gtrsim5$

Understand

We propose two effective parameters that fully characterise galactic-scale structure formation at high redshifts ($z\gtrsim5$) for a variety of dark matter (DM) models that have a primordial cutoff in the matter power spectrum.

• Our description is within the recently proposed ETHOS framework and includes standard thermal Warm DM (WDM) and models with dark acoustic oscillations (DAOs).
• To define and explore this parameter space, we use high-redshift zoom-in simulations that cover a wide range of non-linear scales from those where DM should behave as CDM ($k\sim10\,h\,{\rm Mpc}^{-1}$), down to those characterised by the onset of galaxy formation ($k\sim500\,h\,{\rm Mpc}^{-1}$).
• We show that the two physically motivated parameters $h_{\rm peak}$ and $k_{\rm peak}$, the amplitude and scale of the first DAO peak, respectively, are sufficient to parametrize the linear matter power spectrum and classify the DM models as belonging to effective non-linear structure formation regions.