Aachen 2019 – wissenschaftliches Programm
T 16.3: Vortrag
Montag, 25. März 2019, 16:30–16:45, S16
Testing post-inflation Axion Dark Matter using CMB Observations — •Andreas Pargner1, Martin Feix1,2, Johann Frank1, Robert Reischke1,2, Bjoern Malte Schaefer2, and Thomas Schwetz1 — 1Institut für Kernphysik, Kalsruhe Institute of Technology, Karlsruhe, Germany — 2Zentrum für Astronomie der Universität Heidelberg, Astronomisches Recheninstitut, Heidelberg, Germany
We present a novel way of testing axion dark matter using cosmological observables in scenarios where Peccei-Quinn symmetry breaking happens after inflation. It is known that in these scenarios large isocurvature fluctuations in the axion energy density occur. For typical QCD axions, the scale of these fluctuations is too small to be cosmologically relevant and they are usually studied in the context of axion minicluster formation. However, we argue that for extremely light axions, also known as fuzzy dark matter, the isocurvature fluctuations can be quite sizable and have effects in large-scale observables. Relating the scale of the density fluctuations to the axion mass, we use CMB observations from the Planck mission to show that in certain scenarios fuzzy DM in the mass range 10−24 eV<ma< 10−16 eV can already be ruled out. We also estimate the sensitivity of upcoming CMB Stage IV experiments and 21cm observations on the axion isocurvature fluctuations.