Dark matter

This course describes the theoretical and observational foundations of the problem known as cosmological dark matter. Dark matter manifests itself through gravitational effects at different astrophysical scales, 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, connecting the infinitely small (elementary particles) to the infinitely large (the universe on a large scale).

The objectives are (1) to awaken students to a major modern problem in fundamental physics in a cosmological context, (2) to provide them with an advanced theoretical framework enabling them to gain a solid understanding of this issue, (3) to teach them how to use several fundamental concepts from various disciplines to address a problem that is interdisciplinary in nature (classical mechanics, statistics, fluids, 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, elements of general relativity and cosmology (homogeneous universe).

Terminal exam: Written exam (3 hours).

This course describes the theoretical and observational foundations of the problem known as cosmological dark matter. Dark matter manifests itself through gravitational effects at different astrophysical scales, 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. Despite its mysterious origin, its properties are fundamental to understanding the formation of galaxies.

The course will detail the gravitational signatures of dark matter at different 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 discussion of alternative scenarios will be the main topics covered. The aim is therefore to connect the infinitely small to the infinitely large in a very concrete way. The course will thus provide an overview of the state of the art by comparing relatively recent theoretical developments with observational constraints, reflecting on a research topic that is still exploratory and drawing on a wide variety of physics concepts. The course will be taught at the blackboard (or via videoconference if necessary), where numerous calculations will be detailed, without slides.