A Limit on the Polarized Anomalous Microwave Emission of Lynds 1622

Mason, B. S.; Robishaw, Timothy; Heiles, Carl; Finkbeiner, Douglas P.; Dickinson, C.

doi:10.1088/0004-637x/697/2/1187

Cited by 29 publications

(31 citation statements)

References 30 publications

(37 reference statements)

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“…For the size distribution used to account for the PAH emission features in the infrared results, the predicted rotational emission appears to be in agreement with the observed intensity of dust-correlated microwave emission (e.g., Dobler et al 2009;). There do not appear to be any mechanisms that can effectively align PAH angular momenta with the galactic magnetic field (Lazarian & Draine 2000), and the rotational emission from PAHs is therefore expected to be essentially unpolarized, in agreement with upper limits on the polarization of the dust-correlated microwave emission (Battistelli et al 2006;Mason et al 2009). By contrast, the far-infrared and submm emission from larger grains is expected to have polarizations as large as ∼10% (Draine & Fraisse 2009) -soon to be measured by Planck.…”

Section: Modeling the Ir Emissionsupporting

confidence: 59%

Astronomical Models of PAHs and Dust

Draine

2011

EAS Publications Series

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Abstract. Physical dust models which include a PAH component are quite successful in reproducing the measured extinction vs. wavelength in the Milky Way, the infrared (IR) emission observed from Milky Way regions and other galaxies, and a number of other observational constraints. Many of the adopted PAH properties are necessarily highly idealized.The observed variations in the 7.7 μm/11.3 μm band ratio can be reproduced by varying the PAH ionization balance. Changing the spectrum of the starlight heating the PAHs affects the overall strength of the PAH emission (relative to total IR), but has relatively little effect on the 7.7 μm/11.3 μm band ratio.

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Section: Modeling the Ir Emissionsupporting

confidence: 59%

Astronomical Models of PAHs and Dust

Draine

2011

EAS Publications Series

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“…Fig. 15.-Measured polarization of AME from the Perseus molecular complex (Battistelli et al 2006;Dickinson et al 2011); the dark clouds Lynds 1622 (Mason et al 2009) and ρ Oph (Dickinson et al 2011); the HII regions G159.6-18.5 (López-Caraballo et al 2011;Génova-Santos et al 2015) and RCW176 (Battistelli et al 2015); and the W43r molecular complex (Génova-Santos et al 2016). …”

Section: Discussionmentioning

confidence: 99%

Quantum Suppression of Alignment in Ultrasmall Grains: Microwave Emission From Spinning Dust Will Be Negligibly Polarized

Draine

Hensley

2016

ApJ

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The quantization of energy levels in very nanoparticles suppresses dissipative processes that convert grain rotational kinetic energy into heat. For grains small enough to have ∼GHz rotation rates, the suppression of dissipation can be extreme. As a result, alignment of such grains is suppressed. This applies both to alignment of the grain body with its angular momentum J, and to alignment of J with the local magnetic field B 0 . If the anomalous microwave emission is rotational emission from spinning grains, it will be negligibly polarized at GHz frequencies, with P 10 −6 at ν > 10 GHz.

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“…The only polarization observations of the anomalous emission to date have found low levels. Battistelli et al (2006) report 3.4 +1.5 −1.9 per cent towards the Perseus molecular cloud at 11 GHz, while Mason et al (2009) report an upper limit of 3.5 per cent (99.7 per cent confidence level) towards the dark cloud Lynds 1622 at 9 GHz. López-Caraballo et al (2011) used WMAP data to constrain the polarization towards the Perseus molecular cloud to be less than 1.0, 1.8 and 2.7 per cent at 23, 33 and 41 GHz, respectively.…”

Section: Dustmentioning

confidence: 98%

Galactic foreground contributions to the 5-year Wilkinson Microwave Anisotropy Probe maps

Macellari

Pierpaoli

Dickinson

et al. 2011

Monthly Notices of the Royal Astronomical Society

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We compute the cross‐correlation between intensity and polarization from the 5‐year Wilkinson Microwave Anisotropy Probe (WMAP5) data in different sky regions with respect to template maps for synchrotron, dust and free–free emission. We derive the frequency dependence and polarization fraction for all three components in 48 different sky regions of HEALPix (Nside= 2) pixelization. The anomalous emission associated with dust is clearly detected in intensity over the entire sky at the K (23‐GHz) and Ka (33‐GHz) WMAP bands, and is found to be the dominant foreground at low Galactic latitudes, between b =−40° and +10°. The synchrotron spectral index obtained from the K and Ka WMAP bands from an all‐sky analysis is βs=−3.32 ± 0.12 for intensity and βs=−3.01 ± 0.03 for polarized intensity. The polarization fraction of the synchrotron emission is constant in frequency and increases with latitude from ≈5 per cent near the Galactic plane up to ≈40 per cent in some regions at high latitudes; the average value for |b| < 20° is 8.6 ± 1.7 (stat) ± 0.5 (sys) per cent, while for |b| > 20°, it is 19.3 ± 0.8 (stat) ± 0.5 (sys) per cent. Anomalous dust and free–free emissions appear to be relatively unpolarized. Monte Carlo simulations showed that there were biases of the method due to cross‐talk between the components, at up to ≈5 per cent in any given pixel, and ≈1.5 per cent on average, when the true polarization fraction is low (a few per cent or less). Nevertheless, the average polarization fraction of dust‐correlated emission at the K band is 3.2 ± 0.9 (stat) ± 1.5 (sys) per cent or less than 5 per cent at 95 per cent confidence. When comparing real data with simulations, eight regions show a detected polarization above the 99th percentile of the distribution from simulations with no input foreground polarization, six of which are detected at above 2σ and display polarization fractions between 2.6 and 7.2 per cent, except for one anomalous region, which has 32 ± 12 per cent. The dust polarization values are consistent with the expectation from spinning dust emission, but polarized dust emission from magnetic‐dipole radiation cannot be ruled out. Free–free emission was found to be unpolarized with an upper limit of 3.4 per cent at 95 per cent confidence.

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A Limit on the Polarized Anomalous Microwave Emission of Lynds 1622

Cited by 29 publications

References 30 publications

Astronomical Models of PAHs and Dust

Astronomical Models of PAHs and Dust

Quantum Suppression of Alignment in Ultrasmall Grains: Microwave Emission From Spinning Dust Will Be Negligibly Polarized

Galactic foreground contributions to the 5-year Wilkinson Microwave Anisotropy Probe maps

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