Physical Modeling of Dust Polarization from Magnetically Enhanced Radiative Torque (MRAT) Alignment in Protostellar Cores with POLARIS

Abstract

Magnetic fields ($\text{B}$) are an important factor that controls the star formation process. The leading method to observe $\text{B}$ is using polarized thermal emission from dust grains aligned with $\text{B}$. However, in dense environments such as protostellar cores, dust grains may have inefficient alignment due to strong gas randomizations, so that using dust polarization to trace $\text{B}$ is uncertain. Hoang $\&$ Lazarian (2016) demonstrated that the grain alignment by RAdiative Torques is enhanced if dust grains contain embedded iron inclusions. Here we extend POLARIS code to study the effect of iron inclusions on grain alignment and thermal dust polarization toward a protostellar core, assuming uniform magnetic fields. We found that paramagnetic grains produce a low polarization degree of $p\sim 1\%$ in the envelope and negligible $p\ll 1\%$ in the central region due to the loss of grain alignment. In contrast, grains with a high level of iron inclusions can have perfect alignment and produce high $p\sim 40\%$ in the envelope and low $p\le 10\%$ in the central region. Grains with a moderate level of iron inclusions induce the polarization flipping from $\text{P}$ $\parallel$ $\text{B}$ at millimeter to $\text{P}$ $\perp$ $\text{B}$ at submillimeter due to the change in the internal alignment caused by slow internal relaxation. The weak alignment of very large grains of $a\ge 10\mu m$ reduces the polarization by dichroic extinction at submillimeter wavelengths. We found a positive correlation between p and the level of iron inclusions, which opens a new window to constrain the abundance of irons locked in dust through dust polarimetry.

arXiv comment39 pages, 27 figures

References in corpus (67)

• Theory of Star Formation
• A Unified Representation of Gas-Phase Element Depletions in the Interstellar Medium
• Electric Dipole Radiation from Spinning Dust Grains
• Radiative torques: Analytical Model and Basic Properties
• Rapid Coagulation of Porous Dust Aggregates Outside the Snow Line: A Pathway to Successful Icy Planetesimal Formation
• Planck intermediate results. XIX. An overview of the polarized thermal emission from Galactic dust
• Tracing Magnetic Fields with Aligned Grains
• Magnetic Fields in the Formation of Sun-Like Stars
• Radiative Torques on Interstellar Grains: I. Superthermal Spinup
• Collapse of Magnetized Singular Isothermal Toroids: II. Rotation and Magnetic Braking
• Fluffy dust forms icy planetesimals by static compression
• TADPOL: A 1.3 mm Survey of Dust Polarization in Star-forming Cores and Regions
• Planck 2018 results. XII. Galactic astrophysics using polarized dust emission
• Radiative torque alignment: Essential Physical Processes
• Radiative transfer with POLARIS: I. Analysis of magnetic fields through synthetic dust continuum polarization measurements
• A unified model of grain alignment: radiative alignment of interstellar grains with magnetic inclusions
• Radiative grain alignment in protoplanetary disks: Implications for polarimetric observations
• Grain growth in the envelopes and disks of Class I protostars
• Grain Growth and Density Distribution of the Youngest Protostellar Systems
• IRAS 16293: A "Magnetic" Tale of Two Cores
• The impact of turbulence and magnetic field orientation on star forming filaments
• Grain Alignment by Radiative Torques in Special Conditions and Implications
• Observational Constraints on the Physical Properties of Interstellar Dust in the Post-Planck Era
• Jets and Outflows From Star to Cloud: Observations Confront Theory
• Interferometric observations of magnetic fields in forming stars
• Grain alignment induced by radiative torques: effects of internal relaxation of energy and complex radiation fields
• Iron: A Key Element for Understanding the Origin and Evolution of Interstellar Dust
• Grain Alignment and Polarized Emission from Magnetized T Tauri Disks
• Low dust emissivities and radial variations in the envelopes of Class 0 protostars: a signature of early grain growth?
• The Dielectric Function of "Astrodust" and Predictions for Polarization in the 3.4$\mu$m and 10$\mu$m Features
• ALMA's Polarized View of 10 Protostars in the Perseus Molecular Cloud
• Submillimetre dust polarisation and opacity in the HD163296 protoplanetary ring system
• Polarization of Dust Emission in Clumpy Molecular Clouds and Cores
• Submillimeter and Far-Infrared Polarimetric Observations of Magnetic Fields in Star-Forming Regions
• Magnetic field evolution in Bok globules
• Alignment of Dust with Magnetic Inclusions: Radiative Torques and Superparamagnetic Barnett and Nuclear Relaxation
• Barnett Relaxation in Thermally-Rotating Grains
• Nonsticky Ice at the Origin of the Uniformly Polarized Submillimeter Emission from the HL Tau Disk
• Highly Ordered and Pinched Magnetic Fields in the Class 0 Proto-Binary System L1448 IRS 2
• Exploring Magnetic Field Structure in Star-Forming Cores with Polarization of Thermal Dust Emission
• Grain alignment and disruption by radiative torques in dense molecular clouds and implication for polarization holes
• Polarization of Magnetic Dipole Emission and Spinning Dust Emission from Magnetic Nanoparticles
• Condition for the formation of micron-sized dust grains in dense molecular cloud cores
• Dust coagulation feedback on magnetohydrodynamic resistivities in protostellar collapse
• SMA observations of the polarized dust emission in solar-type Class 0 protostars: the magnetic field properties at envelope scales
• Indirect evidence of significant grain growth in young protostellar envelopes from polarized dust emission
• SILCC-Zoom: Polarisation and depolarisation in molecular clouds
• Disk Formation in Magnetized Dense Cores with Turbulence and Ambipolar Diffusion
• On Internal and External Alignment of Dust Grains in Protostellar Environments
• Magnetic Properties of Dust Grains, Effect of Precession and Radiative Torque Alignment
• A statistical analysis of dust polarization properties in ALMA observations of Class 0 protostellar cores
• Magnetic Properties of Star-Forming Dense Cores
• Resolving Linear Polarization due to Emission and Extinction of Aligned Dust Grains on NGC1333 IRAS4A with JVLA and ALMA
• Alignment and rotational disruption of dust
• The origin of dust polarization in molecular outflows
• On the origins of polarization holes in Bok globules
• Magnetically regulated disk-formation in the inner 100 au region of the Class 0 young stellar object OMC-3/MMS~6 resolved by JVLA and ALMA
• Alignment of irregular grains by radiative torques: efficiency study
• A systematic study of radiative torque grain alignment in the diffuse interstellar medium
• Effects of grain alignment with magnetic fields on grain growth and the structure of dust aggregates
• Detection of Linearly Polarized 6.9 mm Continuum Emission from the Class 0 Young Stellar Object NGC1333 IRAS4A
• The Galactic Plane Infrared Polarization Survey (GPIPS): Data Release 4
• Size limit of superparamagnetic inclusions in dust grains and difficulty of magnetic grain alignment in protoplanetary disks
• Spatially Resolving Substructures within the Massive Envelope around an Intermediate-mass Protostar: MMS 6/OMC-3
• The JCMT BISTRO Survey: Multi-wavelength polarimetry of bright regions in NGC 2071 in the far-infrared/submillimetre range, with POL-2 and HAWC+
• Evolution of Magnetic fields in Bok globules?
• The Transition of Polarized Dust Thermal Emission from the Protostellar Envelope to the Disk Scale

Cited by in corpus (9)

• B-fields And dust in interstelLar fiLAments using Dust POLarization (BALLAD-POL): I. The massive filament G11.11-0.12 observed by SOFIA/HAWC+
• Understanding the Multi-wavelength Thermal Dust Polarisation from the Orion Molecular Cloud in Light of the Radiative Torque Paradigm
• Physical conditions for dust grain alignment in Class 0 protostellar cores II. The role of the radiation field in models aligning/disrupting dust grains
• Evidence of Grain Alignment by Magnetically Enhanced Radiative Torques from Multiwavelength Dust Polarization Modeling of HL Tau
• Synthetic Modelling of Polarized Dust Emission in Intermediate-Mass YSOs: I: Constraining the Role of Iron Inclusions and Inelastic Relaxation on Grain Alignment with ALMA Polarization
• Alignment and Rotational Disruption of Dust Grains in the Galactic Centre Revealed by Polarized Dust Emission
• The magnetic fields of the dusty nuclei and molecular outflows of Arp 220
• Grain alignment and dust evolution physics with polarisation (GRADE-POL). I. Dust polarisation modelling for isolated starless cores
• The role of radiative torques in the molecular cloud core L43