Polarized Submillimeter Emission from Filamentary Molecular Clouds

Fiege, Jason D.

doi:10.1086/317228

Cited by 110 publications

(141 citation statements)

References 25 publications

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“…13) through the rotated simulation cube, following the method in Wardle & Königl (1990), Fiege & Pudritz (2000), Pelkonen et al (2009), andPadovani et al (2012). Because of a number of inconsistencies in the literature, we give the correct derivation in Appendix B, drawing on the works of Lee & Draine (1985) and Wardle & Königl (1990).…”

Section: Simulated Planck Observationsmentioning

confidence: 99%

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Planckintermediate results. XX. Comparison of polarized thermal emission from Galactic dust with simulations of MHD turbulence

Ade

Aghanim

Alina

et al. 2015

A&A

124

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Polarized emission observed by Planck HFI at 353 GHz towards a sample of nearby fields is presented, focusing on the statistics of polarization fractions p and angles ψ. The polarization fractions and column densities in these nearby fields are representative of the range of values obtained over the whole sky. We find that: (i) the largest polarization fractions are reached in the most diffuse fields; (ii) the maximum polarization fraction p max decreases with column density N H in the more opaque fields with N H > 10 21 cm −2 ; and (iii) the polarization fraction along a given line of sight is correlated with the local spatial coherence of the polarization angle. These observations are compared to polarized emission maps computed in simulations of anisotropic magnetohydrodynamical turbulence in which we assume a uniform intrinsic polarization fraction of the dust grains. We find that an estimate of this parameter may be recovered from the maximum polarization fraction p max in diffuse regions where the magnetic field is ordered on large scales and perpendicular to the line of sight. This emphasizes the impact of anisotropies of the magnetic field on the emerging polarization signal. The decrease of the maximum polarization fraction with column density in nearby molecular clouds is well reproduced in the simulations, indicating that it is essentially due to the turbulent structure of the magnetic field: an accumulation of variously polarized structures along the line of sight leads to such an anti-correlation. In the simulations, polarization fractions are also found to anti-correlate with the angle dispersion function S. However, the dispersion of the polarization angle for a given polarization fraction is found to be larger in the simulations than in the observations, suggesting a shortcoming in the physical content of these numerical models. In summary, we find that the turbulent structure of the magnetic field is able to reproduce the main statistical properties of the dust polarization as observed in a variety of nearby clouds, dense cores excluded, and that the large-scale field orientation with respect to the line of sight plays a major role in the quantitative analysis of these statistical properties.

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Section: Simulated Planck Observationsmentioning

confidence: 99%

“…Note that the corrective term in Eq. (5) is incorrectly written in Fiege & Pudritz (2000), Gonçalves et al (2005), Pelkonen et al (2009), andPadovani et al (2012), with p 0 /2 instead of p 0 .…”

Section: Simulated Planck Observationsmentioning

confidence: 99%

Planckintermediate results. XX. Comparison of polarized thermal emission from Galactic dust with simulations of MHD turbulence

Ade

Aghanim

Alina

et al. 2015

A&A

124

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“…For grains without polarisation properties, Stokes I is basically given by Σ. Indeed, the grain properties may vary with density (Fiege & Pudritz 2000), but in the absence of detailed information, unless otherwise specified, we assume α max to be constant and equal to 0.15 in the remainder of this paper, corresponding to a maximum polarisation degree of about 15%, as suggested by GGW05. Higher values has not been observed and lower values appear unable to reproduce observations of the magnetic field of prestellar cores (FGG11).…”

Section: Dust Polarisation Toolsmentioning

confidence: 99%

Adaptable radiative transfer innovations for submillimetre telescopes (ARTIST)

Padovani¹,

Brinch²,

Girart³

et al. 2012

A&A

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We present a new publicly available tool (DustPol) aimed to model the polarised thermal dust emission. The module DustPol, which is publicly available, is part of the ARTIST (Adaptable Radiative Transfer Innovations for Submillimetre Telescopes) package, which also offers tools for modelling the polarisation of line emission together with a model library and a Python-based user interface. DustPol can easily manage analytical as well as pre-gridded models to generate synthetic maps of the Stokes I, Q, and U parameters. These maps are stored in FITS format which is straightforwardly read by the data reduction software used, e.g., by the Atacama Large Millimeter Array (ALMA). This turns DustPol into a powerful engine for the prediction of the expected polarisation features of a source observed with ALMA or the Planck satellite as well as for the interpretation of existing submillimetre observations obtained with other telescopes. DustPol allows the parameterisation of the maximum degree of polarisation and we find that, in a prestellar core, if there is depolarisation, this effect should happen at densities of 10 6 cm −3 or larger. We compare a model generated by DustPol with the observational polarisation data of the low-mass Class 0 object NGC 1333 IRAS 4A, finding that the total and the polarised emission are consistent.

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“…This reminds us of the "" polarization disks ÏÏ that are often observed in the near-IR polarization maps of star-forming regions and are indicative of the disk plane and therefore perpendicular to the outÑow direction (e.g., Tamura et al 1991 ;Lucas & Roche 1998). The direction of the "" submillimeter polarization disk ÏÏ in IRS 1(SMM) roughly coincides with the major axis of the disklike structure observed with molecular emissions (e.g., Scoville et al 1986 ;Kawabe et al 1992), although the origin of such polarization pattern at submillimeter wavelengths is not clear (for the case of a Ðlamentary cloud, see Fiege & Pudritz 2000).…”

Section: Irs 1(smm)mentioning

confidence: 99%

Submillimeter Imaging Polarimetry of the NGC 7538 Region

Momose

Tamura

Kameya

et al. 2001

ApJ

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Imaging polarimetry of the 850 km continuum emission in the NGC 7538 region, obtained with the SCUBA Polarimeter, is presented. The polarization map is interpreted in terms of thermal radiation by magnetically aligned dust grains. Two prominent cores associated with IRS 1 and IRS 11, IRS 1(SMM), and IRS 11(SMM), are found in the surface brightness map. Although these cores look similar in surface brightness, their polarization shows striking di †erences. In IRS 11(SMM), the polarization vectors are extremely well-ordered, and the degrees of polarization are quite high with an average of D3.9%. In IRS 1(SMM), on the other hand, the directions of polarization vectors are locally disturbed, and the degrees of polarization are much lower than those of IRS 11(SMM). These di †erences suggest that small scale Ñuctuations of the magnetic Ðeld are more prominent in IRS 1(SMM). This can be interpreted in terms of the di †erence in evolutionary stage of the cores. Inside IRS 1(SMM), which seems to be at a later evolutionary stage than IRS 11(SMM), substructures such as subclumps or a cluster of infrared sources have already formed. Small scale Ñuctuations in the magnetic Ðeld could have developed during the formation of these substructures. The distribution of magnetic Ðeld directions derived from our polarization map agrees well with those of molecular outÑows associated with IRS 1(SMM) and IRS 11(SMM). Comparisons of energy densities between the magnetic Ðeld and the outÑows show that the magnetic Ðeld probably plays an important role in guiding the directions of the outÑows.

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Polarized Submillimeter Emission from Filamentary Molecular Clouds

Cited by 110 publications

References 25 publications

Planckintermediate results. XX. Comparison of polarized thermal emission from Galactic dust with simulations of MHD turbulence

Planckintermediate results. XX. Comparison of polarized thermal emission from Galactic dust with simulations of MHD turbulence

Adaptable radiative transfer innovations for submillimetre telescopes (ARTIST)

Submillimeter Imaging Polarimetry of the NGC 7538 Region

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