Field excitation in fuzzy dark matter near a strong gravitational wave source

Abstract

The axion-like particles with ultralight mass (∼ 10 −22 eV) can be a possibile candidate of dark matter, known as the fuzzy dark matter (FDM). These particles form Bose-Einstein condensate in the early universe which can explain the dark matter density distribution in galaxies at the present time. We study the time evolution of ultralight axion-like field in the near region of a strong gravitational wave (GW) source, such as binary black hole merger. We show that GWs can lead to the generation of field excitations in a spherical shell about the source that eventually propagate out of the shell to minimize the energy density of the field configuration. These excitations are generated towards the end of the merger and in some cases even in the ringdown phase of the merger, therefore it can provide a qualitatively distinct prediction for changes in the GW waveform observed on Earth. This would be helpful in investigating the existence of FDM in galaxies.

Instabilities of Scalar Fields around Oscillating Stars

“…However, real objects will also have an oscillating density. Thus, the effective mass inside the star will have a periodic time variability, potentially giving rise to "parametric" instabilities [58][59][60][61]. Figure 3 summarizes our results for nonvanishing βδρ.…”