The origin of dust polarization in molecular outflows
arXiv:1703.02932 · doi:10.1051/0004-6361/201730408
Abstract
Aims: In this paper we present a case study to investigate conditions necessary to detect a characteristic magnetic field substructure embedded in a large-scale field. A helical magnetic field with a surrounding hourglass shaped field is expected from theoretical predictions and self-consistent magnetohydrodynamical (MHD) simulations to be present in the specific case of protostellar outflows. Hence, such an outflow environment is the perfect for our study. Methodes: We present synthetic polarisation maps in the infrared and millimeter regime of protostellar outflows performed with the newly developed RT and polarisation code POLARIS. The code, as the first, includes a self-consistent description of various alignement mechanism like the imperfect Davis-Greenstein (IDG) and the radiative torque (RAT) alignment. We investigate for which effects the grain size distribution, and applied alignement mechanism have. Results: We find that the IDG mechanism cannot produce any measurable polarization degree (< 1 %) whereas RAT alignment produced polarization degrees of a few 1 %. Furthermore, we developed a method to identify the origin of the polarization. We show that the helical magnetic field in the outflow can only be observed close to the outflow axis and at its tip, whereas in the surrounding regions the hourglass field in the foreground dominates the polarization. Furthermore, the polarization degree in the outflow lobe is lower than in the surroundings in agreement with observations. We also find that the orientation of the polarization vector flips around a few 100 micron due to the transition from dichroic extinction to thermal re-emission. Hence, in order to avoid ambiguities when interpreting polarization data, we suggest to observed in the far-infrared and mm regime. Finally, we show that with ALMA it is possible to observe the polarization emerging from protostellar outflows.
arXiv comment15 pages, 9 figures
References in corpus (40)
- Infrared Emission from Interstellar Dust. IV. The Silicate-Graphite-PAH Model in the Post-Spitzer Era
- Radiative torques: Analytical Model and Basic Properties
- Tracing Magnetic Fields with Aligned Grains
- Modeling Collapse and Accretion in Turbulent Gas Clouds: Implementation and Comparison of Sink Particles in AMR and SPH
- Magnetic Fields in the Formation of Sun-Like Stars
- Radiative Torques on Interstellar Grains: I. Superthermal Spinup
- Radiative Equilibrium and Temperature Correction in Monte Carlo Radiation Transfer
- The Effects of Radiative Transfer on Low-Mass Star Formation
- Radiative Torques on Interstellar Grains: II. Grain Alignment
- An Imprint of Molecular Cloud Magnetization in the Morphology of the Dust Polarized Emission
- TADPOL: A 1.3 mm Survey of Dust Polarization in Star-forming Cores and Regions
- Radiative torque alignment: Essential Physical Processes
- Radiative transfer with POLARIS: I. Analysis of magnetic fields through synthetic dust continuum polarization measurements
- Polarized Far-Infrared and Submillimeter Emission from Interstellar Dust
- VLBA determination of the distance to nearby star-forming regions II. Hubble 4 and HDE 283572 in Taurus
- Misalignment of Magnetic Fields and Outflows in Protostellar Cores
- Mie Scattering by Ensembles of Particles with Very Large Size Parameters
- A unified model of grain alignment: radiative alignment of interstellar grains with magnetic inclusions
- Collapse-Driven Outflow in Star-Forming Molecular Cores
- Magnetic fields during the early stages of massive star formation - I. Accretion and disk evolution
- High Resolution Millimeter-Wave Mapping of Linearly Polarized Dust Emission: Magnetic Field Structure in Orion
- Modelling Dust Evolution in Galaxies with a Multiphase, Inhomogeneous ISM
- On the Distance to the Ophiuchus Star-Forming Region
- Dust Grain-Size Distributions From MRN to MEM
- Alignment Between Flattened Protostellar Infall Envelopes and Ambient Magnetic Fields
- Grain alignment induced by radiative torques: effects of internal relaxation of energy and complex radiation fields
- Magnetic fields during the early stages of massive star formation - II. A generalised outflow criterion
- Supersonic turbulence, filamentary accretion,and the rapid assembly of massive stars and disks
- Barnett Relaxation in Thermally-Rotating Grains
- Magnetic Field Structure around Low-Mass Class 0 Protostars: B335, L1527 and IC348-SMM2
- Radiative Torques on Interstellar Grains. III. Dynamics with Thermal Relaxation
- Helical Magnetic Fields in the NGC1333 IRAS 4A Protostellar Outflows
- Comparing star formation models with interferometric observations of the protostar NGC 1333 IRAS 4A. I. Magnetohydrodynamic collapse models
- Condition for the formation of micron-sized dust grains in dense molecular cloud cores
- A Massive Bipolar Outflow and a Dusty Torus with Large Grains in the Pre-Planetary Nebula IRAS 22036+5306
- Adaptable Radiative Transfer Innovations for Submillimetre Telescopes (ARTIST) - Dust polarisation module (DustPol)
- Angle-dependent radiative grain alignment; Confirmation of a magnetic field - radiation anisotropy angle dependence on the efficiency of interstellar grain alignment
- Tracing the ISM magnetic field morphology: The potential of multi-wavelength polarization measurements
- Origin of Molecular Outflow Determined from Thermal Dust Polarization
- Mapping the Linearly Polarized Spectral Line Emission around the Evolved Star IRC+10216
Cited by in corpus (24)
- The Role of Magnetic Fields in Protostellar Outflows and Star Formation
- Magnetized filamentary gas flows feeding the young embedded cluster in Serpens South
- From parallel to perpendicular -- On the orientation of magnetic fields in molecular clouds
- Characterizing magnetic field morphologies in three Serpens protostellar cores with ALMA
- SILCC-Zoom: Polarisation and depolarisation in molecular clouds
- WARPFIELD-EMP: The Self-Consistent Prediction of Emission Lines from Evolving HII Regions in Dense Molecular Clouds
- Resolving Linear Polarization due to Emission and Extinction of Aligned Dust Grains on NGC1333 IRAS4A with JVLA and ALMA
- WARPFIELD Population Synthesis: The physics of (extra-)Galactic star formation and feedback driven cloud structure and emission from sub-to-kpc scales
- Radiative transfer with POLARIS. II.: Modeling of synthetic Galactic synchrotron observations
- Magnetic fields in star forming systems (I): Idealized synthetic signatures of dust polarization and Zeeman splitting in filaments
- 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
- Physical Modeling of Dust Polarization from Magnetically Enhanced Radiative Torque (MRAT) Alignment in Protostellar Cores with POLARIS
- Dynamical Ejections of Stars due to an Accelerating Gas Filament
- Magnetic fields in star-forming systems (II): examining dust polarization, the Zeeman effect, and the Faraday rotation measure as magnetic field tracers
- Synthetic observations of spiral arm tracers of a simulated Milky Way analog
- Three-dimensional continuum radiative transfer of polarized radiation in exoplanetary atmospheres
- Is the mm/submm dust polarization a robust tracer of the magnetic field topology in protostellar envelopes? A model exploration
- Linear dust polarization during the embedded phase of protostar formation
- Synthetic observations of dust emission and polarisation of Galactic cold clumps
- Physical conditions for dust grain alignment in Class 0 protostellar cores II. The role of the radiation field in models aligning/disrupting dust grains
- Optical depth in polarised Monte Carlo radiative transfer
- Wavelength-dependent far-infrared polarization of HL Tau observed with SOFIA/HAWC+
- GTC/CanariCam Mid-IR Polarimetry of Magnetic Fields in Star-Forming Region W51 IRS2
- Synthetic Polarization Maps of an Outflow Zone from Magnetohydrodynamic Simulations