ETHOS - An Effective Theory of Structure Formation: From dark particle physics to the matter distribution of the Universe

TL;DR

ETHOS provides a versatile framework linking dark matter microphysics to cosmic structure formation, enabling efficient simulation and classification of dark matter models based on their impact on the universe's matter distribution.

Contribution

This work introduces ETHOS, an effective theory that maps dark matter particle physics into parameters influencing structure formation, facilitating comparison and simulation of diverse models.

Findings

Mapped various dark matter models to effective parameters affecting structure formation

Proposed a simple parametrization for dark matter self-interactions in simulations

Demonstrated that models with similar effective parameters produce similar cosmic structures

Abstract

We formulate an effective theory of structure formation (ETHOS) that enables cosmological structure formation to be computed in almost any microphysical model of dark matter physics. This framework maps the detailed microphysical theories of particle dark matter interactions into the physical effective parameters that shape the linear matter power spectrum and the self-interaction transfer cross section of non-relativistic dark matter. These are the input to structure formation simulations, which follow the evolution of the cosmological and galactic dark matter distributions. Models with similar effective parameters in ETHOS but with different dark particle physics would nevertheless result in similar dark matter distributions. We present a general method to map an ultraviolet complete or effective field theory of low energy dark matter physics into parameters that affect the linear matter power spectrum and carry out this mapping for several representative particle models. We further propose a simple but useful choice for characterizing the dark matter self-interaction transfer cross section that parametrizes self-scattering in structure formation simulations. Taken together, these effective parameters in ETHOS allow the classification of dark matter theories according to their structure formation properties rather than their intrinsic particle properties, paving the way for future simulations to span the space of viable dark matter physics relevant for structure formation.