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Magnetic fields (B-fields) in galaxies have recently been traced using far-infrared and sub-mm polarimetric observations with SOFIA, JCMT, and ALMA. The main assumption is that dust grains are magnetically aligned with the local B-field in…

Astrophysics of Galaxies · Physics 2024-03-01 Enrique Lopez-Rodriguez , Le Ngoc Tram

(abridged) The polarized thermal radiation at far infrared and submillimeter wavelengths from dust grains in interstellar clouds with irregular magnetic fields is simulated. We show that the polarization properties of quiescent clouds and…

Astrophysics · Physics 2009-11-10 D. S. Wiebe , W. D. Watson

Dust grains drift through the interstellar medium (ISM) and are aligned with the magnetic field. Here we study the effect of grain alignment and grain motion on grain growth in molecular clouds (MCs). We first discuss the characteristic…

Astrophysics of Galaxies · Physics 2022-04-06 Thiem Hoang

Interstellar linear polarization occurs when starlight passes through elongated dust grains aligned by interstellar magnetic fields. The observed polarization can come from different dust structures along the line of sight (LOS). By…

Galactic dust emission is polarized at unexpectedly high levels, as revealed by Planck. The origin of the observed $\simeq 20\%$ polarization fractions can be identified by characterizing the properties of optical starlight polarization in…

Astrophysics of Galaxies · Physics 2019-04-17 G. V. Panopoulou , B. S. Hensley , R. Skalidis , D. Blinov , K. Tassis

We study the efficiency of grain alignment by radiative torques (RATs) for an ensemble of irregular grains. The grains are modeled as ensembles of oblate and prolate spheroids, deformed as Gaussian random ellipsoids, and their scattering…

Astrophysics of Galaxies · Physics 2021-06-02 Joonas Herranen , A. Lazarian , Thiem Hoang

Radiative Torques (RATs) or Mechanical Torques (METs) acting on irregular grains can induce the alignment of dust grains in respect to the alignment axis (AA), which can be either the direction of the magnetic field, or the direction of the…

Astrophysics of Galaxies · Physics 2020-10-21 A. Lazarian

$\textit{Aims.}$ We present a case study to demonstrate the potential of multi-wavelength polarization measurements. The aim is to investigate the effects that dichroic polarization and thermal re-emission have on tracing the magnetic field…

Solar and Stellar Astrophysics · Physics 2015-06-19 S. Reissl , S. Wolf , D. Seifried

Recent observation of 850 micron sub-mm polarization from T Tauri disks opens up the possibility of studying magnetic field structure within protostellar disks. The degree of polarization is around 3 % and the direction of polarization is…

Solar and Stellar Astrophysics · Physics 2009-01-21 Jungyeon Cho , A. Lazarian

We apply the theory of radiative torque (RAT) alignment for studying protoplanetary disks around a T-Tauri star and perform 3D radiative transfer calculations to provide the expected maps of polarized radiation to be compared with…

Earth and Planetary Astrophysics · Physics 2017-04-19 Ryo Tazaki , Alexandre Lazarian , Hideko Nomura

Three-dimensional magnetic fields (3D B-fields) are essential to understand the formation and evolution of the interstellar medium and multi-scale star formation; however, the accurate measurement of 3D B-fields is still challenging. The…

Astrophysics of Galaxies · Physics 2025-10-09 Bao Truong , Thiem Hoang , Nguyen Bich Ngoc , Nguyen Chau Giang , Le Ngoc Tram , Ngan Le

Variations in polarization efficiency (p/A) of interstellar grains as a function of environment place vital constraints on models for the mechanism of their alignment. We use polarimetry of background field stars to investigate alignment in…

Astrophysics · Physics 2009-10-28 P. A. Gerakines , D. C. B. Whittet

The observations of fluctuations in the cosmic microwave background provide information about primordial inhomogeneities in the universe. However, the B-mode polarization of the inflationary gravitational wave is contaminated by the…

Cosmology and Nongalactic Astrophysics · Physics 2020-01-29 Yue Hu , Ka Ho Yuen , Alex Lazarian

We present a model for the diffuse interstellar dust that explains the observed wavelength-dependence of extinction, emission, linear and circular polarisation of light. The model is set-up with a small number of parameters. It consists of…

Astrophysics of Galaxies · Physics 2015-06-16 R. Siebenmorgen , N. V. Voshchinnikov , S. Bagnulo

Polarized emission from aligned dust is a crucial tool for studies of magnetism in the ISM and a troublesome contaminant for studies of CMB polarization. In each case, an understanding of the significance of the polarization signal requires…

The understanding of (sub-)millimetre polarisation has made a leap forward since high-resolution imaging with ALMA came available. Amongst other effects, self-scattering (i.e., scattering of thermal dust emission on other grains) is thought…

Solar and Stellar Astrophysics · Physics 2020-07-01 Florian Kirchschlager , Gesa H. -M. Bertrang

We present synthetic dust polarisation maps of 3D magneto-hydrodynamical simulations of molecular clouds before the onset of stellar feedback. The clouds are modelled within the SILCC-Zoom project and are embedded in their galactic…

Astrophysics of Galaxies · Physics 2018-10-31 D. Seifried , S. Walch , S. Reissl , J. C. Ibáñez-Mejía

We present 870 $\mu$m ALMA polarization observations of thermal dust emission from the iconic, edge-on debris disk $\beta$ Pic. While the spatially resolved map does not exhibit detectable polarized dust emission, we detect polarization at…

We present a statistical analysis of the interstellar medium (ISM) polarization from the largest compilation available of starlight data, which comprises ~ 5500 stars. The measured correlation between the mean polarization degree and…

Astrophysics · Physics 2014-10-13 Pablo Fosalba , Alex Lazarian , Simon Prunet , Jan A. Tauber

We present a new method to constrain the grain size in protoplanetary disks with polarization observations at millimeter wavelengths. If dust grains are grown to the size comparable to the wavelengths, the dust grains are expected to have a…

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