Signatures of Fuzzy Dark Matter Inside Radial Critical Curves

TL;DR

This paper explores how fuzzy dark matter (FDM) alters gravitational lensing near radial critical curves, revealing distinctive magnification features that could help distinguish FDM from standard cold dark matter in astrophysical observations.

Contribution

The study demonstrates that FDM produces unique lensing signatures near radial critical curves, dependent on axion mass, which are not replicated by cold dark matter models.

Findings

FDM causes enhanced central magnification near radial critical curves.

Secondary critical curves are more prominent in FDM than in CDM.

Distinct magnification distributions for axion masses around 10^{-22} to 10^{-21} eV.

Abstract

We investigate the strong gravitational lensing properties of fuzzy dark matter (FDM) halos, focusing on the magnification properties near radial critical curves (CCs). Using simulated lenses we compute magnification maps for a range of axion masses and halo configurations. We show that FDM produces enhanced central magnification and secondary CCs that are not easily reproduced by standard cold dark matter (CDM), even when including subhalos. The strength and scale of these effects depend primarily on the de~Broglie wavelength, governed by the axion and halo masses. We find that axion masses in the range $m_\psi \sim 10^{-22}$--$10^{-21}\,\mathrm{eV}$ in galaxy-mass halos lead to distinctive magnification distributions. Our results suggest that observations of highly magnified, compact sources near radial arcs, such as quasars or supernovae, could serve as a powerful test for the presence of FDM.