Lectures on Light Particles and Compact Objects

TL;DR

This paper reviews methods for detecting axions, axion-like particles, and high-frequency gravitational waves using compact astrophysical objects, emphasizing recent search strategies and practical exercises.

Contribution

It provides an overview of astrophysical search techniques for WISPs and high-frequency gravitational waves, with new insights into neutron stars, superradiance, and white dwarf observations.

Findings

Enhanced understanding of axion detection via neutron stars and white dwarfs

Discussion of superradiance as a detection mechanism

Practical exercises for astrophysical searches included

Abstract

This document is based on lectures delivered at a recent COSMIC WISPers COST Action training school in Annecy in September 2025. They examine detection of weakly interacting slim particles (WISPs), specifically axions and high-frequency gravitational waves, with compact objects. These slightly expanded notes focus on searches for axion dark matter and axion-like particles with neutron stars, superradiance, white dwarfs and astrophysical searches for high-frequency gravitational waves. They are accompanied by a set of practical exercises. Comments on these notes are gratefully received.