  A widely-held assumption is that each single white dwarf containing
observable rocky debris requires the presence of at least one terrestrial or
giant planet to have gravitationally perturbed the progenitor of the debris
into the star. However, these planets could have been previously been engulfed
by the star or escaped the system, leaving behind asteroids, boulders, cobbles,
pebbles, sand and dust. These remaining small bodies could then persist
throughout the host star's evolution into a white dwarf at ~2-100 au scales,
and then be radiatively dragged into the white dwarf without the help of a
planet. Here we identify the parameter space and cooling ages for which this
one metal-pollution mechanism is feasible by, for the first time, coupling
Poynting-Robertson drag, the Yarkovsky effect and the YORP effect solely from
rapidly dimming white dwarf radiation. We find that this no-planet pollution
scenario is efficient for remnant 10^{-5}-10^{-4} m dust up to about 80 au,
10^{-4}-10^{-3} m sand up to about 25 au and 10^{-3}-10^{-2} m small pebbles up
to about 8 au, and perhaps 10^{-1}-10^{0} m small boulders up to tens of au.
Further, young white dwarf radiation can spin up large strength-less boulders
with radii 10^{2}-10^{3} m to destruction, breaking them down into smaller
fragments which then can be dragged towards the white dwarf. Our work hence
introduces a planet-less metal-pollution mechanism that may be active in some
fraction of white dwarf planetary systems.
