Radiative torques of irregular grains: Describing the alignment of a grain ensemble

Abstract

The radiative torque (RAT) mechanism is the most promising way of explaining observed polarization arising from aligned grains. We explore the efficiency of the grain alignment by an anisotropic radiation flow for an extensive ensemble of grain shapes. We calculate the distribution of the ratios of the amplitudes of the two major components of the RATs, that is an essential parameter that enters the theory of RAT alignment in Lazarian & Hoang (2007, LH07). While this distribution is different for different classes of grain shapes that we considered, the most probable values of the parameter are centered in the range of $q^{max}\sim 0.5-1.5$. The functional form from RATs calculated is in good agreement with the analytical model (AMO). We find that the RAT efficiency scales as $(\lambda /a{)}^{-3}$ for $\lambda \gg a$ as previously found in LH07. This increases the power of predictions obtained with the RAT theory. We also confirm that superparamagnetic inclusions are necessary in achieving high degrees of alignment, and constrain the parameter space describing the requirements for achieving these alignment degrees.

References in corpus (4)

• Radiative torques: Analytical Model and Basic Properties
• Radiative torque alignment: Essential Physical Processes
• Subsonic Mechanical Alignment of Irregular Grains
• Alignment of Dust with Magnetic Inclusions: Radiative Torques and Superparamagnetic Barnett and Nuclear Relaxation

Cited by in corpus (22)

• Grain alignment and disruption by radiative torques in dense molecular clouds and implication for polarization holes
• Physical Model of Dust Polarization by Radiative Torque Alignment and Disruption and Implications for Grain Internal Structures
• Alignment and rotational disruption of dust
• Alignment of irregular grains by radiative torques: efficiency study
• A systematic study of radiative torque grain alignment in the diffuse interstellar medium
• Constraining the magnetic field properties of Bok globule B335 using SOFIA/HAWC+
• Two modes of carbonaceous dust alignment
• Magnetic fields in star-forming systems (II): examining dust polarization, the Zeeman effect, and the Faraday rotation measure as magnetic field tracers
• Variation of dust properties with cosmic time implied by radiative torque disruption
• Gamma-ray Burst Afterglows: Time-Varying Extinction, Polarization, and Colors due to Rotational Disruption of Dust Grains
• Rotational Disruption of Nonspherical Cometary Dust Particles by Radiative Torques
• Ultraviolet Spectropolarimetry with Polstar: Interstellar Medium Science
• Synthetic dust polarization emission maps at 353 GHz for an observer placed inside a Local Bubble-like cavity
• The rotational disruption of porous dust aggregates from ab-initio kinematic calculations
• The radiative torque spin-up efficiency of ballistic dust grain aggregates
• Effect of Dust Rotational Disruption by Radiative Torques and Implications for F-corona decrease revealed by the Parker Solar Probe
• Evolution of Dust and Water Ice in Cometary Comae by Radiative Torques
• Wavelength-dependent far-infrared polarization of HL Tau observed with SOFIA/HAWC+
• Rotational Disruption of Dust and Ice by Radiative Torques in Protoplanetary Disks and Implications for Observations
• Grain alignment and dust evolution physics with polarisation (GRADE-POL). I. Dust polarisation modelling for isolated starless cores
• Effect of dust rotational disruption by radiative torques on radiation pressure feedback from massive protostars
• Constraining properties of dust formed in Wolf-Rayet binary WR 112 using mid-infrared and millimeter observations