Generating the wide sequence of Diffuse Galaxies with de Broglie waves of Dark Matter

RESUMO

Extensive Euclid satellite imaging at low surface brightness has revealed that most nearby galaxies are diffuse-looking spheroids, where the stellar radius increases monotonically over three decades in luminosity. We argue this Diffuse Galaxy sequence results from internal stellar diffusion by Wave Dark Matter ($\psi$DM), as wave energy is transferred to star orbits over time. In particular, the soliton random motion scatters central stars onto radial orbits that become enhanced with each passage through the centre, slowly "puffing up" the stellar profile. Heating is greater within massive galaxies as $\psi$DM fluctuations are stronger and more frequent, reproducing the Diffuse Galaxy sequence and also accounts for the rising velocity dispersion along the sequence, from Ultra-Faint to Dwarf Spheroidal and Ultra Diffuse galaxies, favouring a light boson, $m_\psi=2.88^{+0.14}_{-0.13}\times10^{-22}$eV. Winding back this diffusion, we predict the stellar content of Diffuse Galaxies, including globular clusters, formed near the centre, as anticipated by $\psi$DM simulations, where gas cools efficiently within the dense soliton. This predicted $\psi$DM evolution from compact beginnings towards diffuse-looking spheroidal galaxies today can now be fully charted from JWST to Euclid.