Axion-like particles and galaxy cluster X-rays as a window to the dark sector
by
DrDavid Marsh(Stockholm University)
→
Europe/Stockholm
122:026
122:026
Description
Axion-like particles (ALPs) can convert into photons in the
presence of coherent background magnetic fields. Galaxy clusters are the
largest gravitationally bound objects in the universe and support magnetic
fields that are coherent over kiloparsec scales. In this talk, I will
discuss how the conversion of ALPs into X-ray photons in clusters of
galaxies provide a window to the dark sector, and in particular how the
different observations (null and otherwise) of an X-ray line at 3.5 keV
from galaxies and clusters are consistent with a scenario in which dark
matter decays into ALPs that subsequently convert into photons in
astrophysical magnetic fields. Furthermore, I will mention how a cosmic
background of relativistic ALPs is a generic outcome in known classes of
stabilised string compactifications, and how such ³dark radiation², if
present, may explain the longstanding question of the nature of the soft
X-ray excess in clusters of galaxies.