Dark Matter

This course describes the theoretical and observational foundations of the so-called cosmological dark matter problem. Dark matter manifests itself through gravitational effects at various astrophysical scales, ranging from the scale of galaxies to cosmological scales (the observable universe as a whole). It constitutes approximately 85% of the total matter in the universe, and it is impossible for it to be composed of the elementary particles that characterize ordinary, known matter. The course will focus in particular on potential solutions to this problem that connect the infinitely small (elementary particles) to the infinitely large (the large-scale universe).

The objectives are (1) to introduce students to a major contemporary problem in fundamental physics within a cosmological context, (2) to provide them with an advanced theoretical framework that will give them a solid foundation for understanding this issue, (3) to teach them how to apply several fundamental concepts from various disciplines to address a problem that is inherently interdisciplinary (classical mechanics, statistics, fluid dynamics, thermodynamics, quantum field theory, general relativity, etc.).

Required prerequisites*:

Differential and integral calculus, differential equations, classical mechanics, statistical mechanics, fluid mechanics, thermodynamics, special relativity.

Recommended prerequisites:

Particle physics, fundamentals of general relativity and cosmology (homogeneous universe).

Final Exam: Written exam (3 hours).

This course describes the theoretical and observational foundations of the so-called cosmological dark matter problem. Dark matter manifests itself through gravitational effects at various astrophysical scales, ranging from the galactic scale to cosmological scales (the observable universe as a whole). It constitutes approximately 85% of the total matter in the universe, and it is impossible for it to be composed of the elementary particles that characterize known ordinary matter. Despite its mysterious origin, its properties are nonetheless fundamental to understanding the formation of galaxies.

The course will detail the gravitational signatures of dark matter at various astrophysical scales and explore a scenario in which it originates from exotic particles produced thermally in the early universe: thermal production, chemical and kinetic decoupling in the early universe, direct and indirect searches, and a discussion of alternative scenarios will be the main topics covered. The goal is thus to establish a very concrete connection between the infinitely small and the infinitely large. The course will provide an overview of the state of the art by comparing relatively recent theoretical developments with observational constraints, reflecting a research topic that remains exploratory and draws on an extremely wide range of physical concepts. The course will be taught at the blackboard (or via videoconference if necessary), where numerous calculations will be worked out in detail, without the use of slides.