Dark Matter in Astrophysics/Cosmology

Abstract

These lecture notes aim to provide an introduction to dark matter from the perspective of astrophysics/cosmology. We start with a rapid overview of cosmology, including the evolution of the Universe, its thermal history and structure formation. Then we look at the observational evidence for dark matter, from observations of galaxies, galaxy clusters, the anisotropies in the cosmic microwave background radiation and large scale structure. To detect dark matter we need to know how it's distributed, in particular in the Milky Way, so next we overview relevant results from numerical simulations and observations. Finally, we conclude by looking at what astrophysical and cosmological observations can tell us about the nature of dark matter, focusing on two particular cases: warm and self-interacting dark matter.

Snowmass2021 Cosmic Frontier White Paper: Cosmological Simulations for Dark Matter Physics

“…Forty years ago, when paired with observations, simulations showed that neutrinos could not be the dominant component of DM, and that something like cold DM described the universe on large scales [288][289][290]. This observation fueled excitement for finding a DM candidate in newfangled supersymmetry theory [291], leading to years of work by particle physicists to characterize the physical effects of neutralinos and other particles in astronomical objects and laboratory searches [11][12][13]292]. In the past twenty years, unexpected astronomical discoveries fueled a new wave of particle modeling building and inspired the next generation of ever-more-sophisticated simulations to connect the physics of DM and gas to observations [38,293].…”

Mono-γ production of a dark vector at future e + e − colliders*

“…. In contrast with the photon-like operator (2), whose contribution to the cross section of the mono-γ process decreases by at high energy, the Pauli operator (3) can initiate the mono-γ signal at a constant rate. Therefore, in dimensional analysis, the significance of the Pauli operator is considerably larger than that of the photon-like operator at high energy colliders, as long as the EFT description is valid.…”

“…The gravitational effects of dark matter (DM) have been unambiguously observed in astrophysical and cosmological measurements [1][2][3]. Moreover, DM is an excellent candidate for explaining several fundamental theoretical questions in the standard model (SM).…”

Inferring dark matter substructure with astrometric lensing beyond the power spectrum

“…All inputs are normalized to zero mean and unit standard deviation across the training sample. Starting with 2 scalar input channels representing the two orthogonal (Galactic latitude and longitude) components of the velocity vector map, 1 we perform a graph convolution operation, increasing the channel dimension to 16 followed by a batch normalization, ReLU nonlinearity, and downsampling the representation by a factor of 4 with max pooling into the next coarser HEALPix resolution. Pooling leverages scale separation, preserving important characteristics of the signal across different resolutions.…”

“…Although there exists plenty of evidence for dark matter (DM) on galactic scales and above (see Ref. [1] for a recent overview), the distribution of DM clumps-subhalos-on sub-galactic scales is less well-understood and remains an active area of cosmological study. This distribution additionally correlates with and may provide clues about the underlying particle physics nature of dark matter (see e.g., Refs.…”