Rotational Disruption of Dust Grains by Radiative Torques in Strong
  Radiation Fields
  Massive stars, supernovae, and kilonovae are among the most luminous
radiation sources in the universe. Observations usually show near- to
mid-infrared (NIR--MIR, $\lambda\sim 1-5~\mu$m) emission excess from H\,{\sc
ii} regions around young massive star clusters (YMSCs). Early phase
observations in optical to NIR wavelengths of type Ia supernovae also reveal
unusual properties of dust extinction and dust polarization. The popular
explanation for such NIR-MIR excess and unusual dust properties is the
predominance of small grains (size $a\lesssim 0.05~\mu$m) relative to large
grains ($a\gtrsim 0.1~\mu$m) in the local environment of these strong radiation
sources. The question of why small grains are predominant in these environments
remains a mystery. Here we report a new mechanism of dust destruction based on
centrifugal stress within extremely fast-rotating grains spun-up by radiative
torques, which we term the RAdiative Torque Disruption (RATD) mechanism. We
find that RATD can disrupt large grains located within a distance of $\sim 1$
pc from a massive star of luminosity $L\sim 10^{4}L_{\odot}$ or a supernova.
This effect increases the abundance of small grains relative to large grains
and successfully reproduces the observed NIR-MIR excess and anomalous dust
extinction/polarization. We apply the RATD mechanism for kilonovae and find
that dust within $\sim$ 0.1 pc would be dominated by small grains. Small grains
produced by RATD can also explain the steep far-UV rise in extinction curves
toward starburst and high redshift galaxies, and the decrease of the escape
fraction of Ly$\alpha$ photons from H\,{\sc ii} regions surrounding YMSCs.
