Small scale structures in coupled scalar field dark matter

We investigate structure formation for ultra-light scalar field dark matter coupled to quintessence, in particular the cosmon–bolon system. The linear power spectrum is computed by a numerical solution of the coupled field equations. We infer the substructure abundance within a Milky Way-like halo. Estimates of dark halo abundances from recent galaxy surveys imply a lower bound on the bolon mass of about 9×10−22 eV9×10−22 eV. This seems to exclude a possible detection of scalar field dark matter through time variation in pulsar timing signals in the near future.