My Research Interests

Dust Dynamics: Grain Acceleration

Research on exoplanets and planetary systems recently become an increasingly hot topic among the astrophysics community; and principal mechanisms underlying the planetesimal formation are strongly debated. Dust coagulation is widely believed to be the first step during the process of planetesimal formation. My research has focused on the acceleration of charged grains, which allows us to better understand the rate of dust coagulation and planetesimal formation, eventually.

For grains larger than 0.1 micron, Hoang, Lazarian, and Schlickeiser (2012) identified that the fast modes of MHD turbulence can efficiently accelerate them through transit-time damping (TTD), which arises from resonant interactions of particles with the compressive component of magnetic fluctuations (i.e., the component parallel to the mean magnetic field). For smaller grains, Hoang and Lazarian (2012) find that acceleration of very small dust grains due to random charge fluctuations.

My recent work (Hoang, Lazarian, and Schlickeiser 2015) shows that dust grains can be accelerated by powerful radiation pressure to speeds close to that of light, which may act as primary particles of ultrahigh energy cosmic rays if relativistic dust could survive their journey to Earth. Our quantitative calculations show that relativistic dust has little chance surviving in the interstellar medium due to Coulomb explosions.

Publications

  1. Hoang Thiem, Lazarian A., and Schlickeiser, R., On Origin and Destruction of Relativistic Dust and its Implication for Ultrahigh Energy Cosmic Rays," 2015, Astrophysical Journal, 806, 255
  2. Hoang Thiem, Lazarian A., Numerical Studies for Acceleration of small dust grains due to charge fluctuations," 2012, Astrophysical Journal, 761, 96
  3. Hoang Thiem, Lazarian A., Schlickeiser R., Revisiting acceleration of charged grains in MHD turbulence," 2012, Astrophysical Journal, 747, 54
  4. Ivlev, A., Lazarian, A., Tsytovich, V.N., de Angelis, U., Hoang Thiem, Morfill, G.E., "Acceleration of Small Astrophysical Grains due to Charge Fluctuations," 2010, Astrophysical Journal, 723, 612