Black matter

This course describes the theoretical and observational foundations of the cosmological dark matter problem. Cosmological dark matter manifests itself through gravitational effects at different astrophysical scales, from galactic to cosmological (the observable universe as a whole). It makes up around 85% of the total matter in the universe, and it is excluded that it is composed of the elementary particles that characterize known ordinary matter. The course will focus on potential solutions to this problem, connecting the infinitely small (elementary particles) to the infinitely large (large-scale universe).

The objectives are (1) to awaken students to a major modern problem of fundamental physics in a cosmological context, (2) to provide them with an advanced theoretical corpus giving them a solid basis for understanding this problem, (3) to teach them how to make use of several fundamental concepts from different disciplines to tackle a problem that is interdisciplinary in nature (classical mechanics, statistics, fluids, thermodynamics, quantum field theory, general relativity, etc.).

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).

Final exam: Written exam (3h).

This course describes the theoretical and observational foundations of the cosmological dark matter problem. Cosmological dark matter manifests itself through gravitational effects at different astrophysical scales, from galactic to cosmological (the observable universe as a whole). It makes up around 85% of the total matter in the universe, and cannot possibly be composed of the elementary particles that characterize known ordinary matter. Despite its mysterious origin, its properties are fundamental to understanding galaxy formation.

The course will detail the gravitational signatures of dark matter at different astrophysical scales, and explore a scenario in which it would find its origin in exotic particles thermally produced in the primordial universe: thermal production, chemical and kinetic decoupling in the primordial universe, direct and indirect searches, and discussion of alternative scenarios, will be the main points covered. The aim is to provide a concrete link 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 is still exploratory and calls on extremely varied physics concepts. The lecture will be given at the blackboard (or by videoconference if necessary), where numerous calculations will be detailed, without slides.