  The coherent oscillation of ultralight dark matter in the mass regime around
$10^{-23}$ eV induces changes in gravitational potential with the frequency in
the nanohertz range. This effect is known to produce a monochromatic signal in
the pulsar timing residuals. Here we discuss a multifield scenario that
produces a wide spectrum of frequencies, such that the ultralight particle
oscillation can mimic the pulsar timing signal of stochastic common spectrum
process. We discuss how ultralight dark matter with various spins produces such
a wide band spectrum on pulsar timing residuals and perform the Bayesian
analysis to constrain the parameters. It turns out that the stochastic
background detected by NANOGrav can be associated with a wideband ultralight
dark matter.
