In order to introduce myself as a new Ramón y Cajal fellow at IFIC, I will give a talk about my recent research, which mostly deals with dark matter and gravitational waves. In the first part, I will discuss the Gertsenshtein effect, or the interconversion of gravitational waves into electromagnetic waves in the presence of external magnetic (or electric) fields. After highlighting the close analogy with axion dark matter,
I will focus on the cosmological implications and examine gamma-ray observations by Fermi-LAT and HESS suggesting the existence of a non-vanishing cosmic magnetic field. Then, I will show how the non-observation of CMB distortions arising from the corresponding conversions can be used to place competitive bounds on high-frequency gravitational waves.
In the second part, I will argue that the Gertsenshtein effect is just a particular realization of gravitational-wave electrodynamics, with more effects to be explored. In particular, exploiting the analogy with axion electrodynamics I will show that axion haloscopes based on lumped-element detectors can probe gravitational waves in the 100 kHz-100 MHz range. Finally, I will discuss the corresponding detection prospects of primordial-black-hole binaries.
IFIC seminar organizers