New constraints on the polarization of anomalous microwave emission in nearby molecular clouds

Dickinson, C.; Peel, M.; Vidal, M.

doi:10.1111/j.1745-3933.2011.01138.x

Cited by 49 publications

(48 citation statements)

References 37 publications

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“…The best constraint comes from the Perseus region, which has significant AME emission and relatively little contaminating synchrotron emission. Battistelli et al (2006) reported a weak detection in Perseus at 3.4 +1.5 −1.9 % at 11 GHz, while later measurements obtained by López-Caraballo et al (2011) using WMAP data found a 2σ limit of <1%; Dickinson et al (2011) have also measured a 2σ limit of <1.4% for Perseus (as well as an upper limit of <1.7% in ρ Ophiuchus), and Génova- Santos et al (2015) found a 2σ limit of <2.8% in Perseus at 19 GHz. Recently, Battistelli et al (2015) have claimed to detect polarized AME emission at 21.5 GHz from RCW 175, an H ii region, where they measured a polarization percentage of (2.2 ± 0.2 (random) ± 0.3 (systematic))% at 21.5 GHz.…”

Section: Limits On Ame Polarizationmentioning

confidence: 98%

Planck2015 results

Ade

Aghanim

Alves

et al. 2016

A&A

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162

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We discuss the Galactic foreground emission between 20 and 100 GHz based on observations by Planck and WMAP. The total intensity in this part of the spectrum is dominated by free-free and spinning dust emission, whereas the polarized intensity is dominated by synchrotron emission. The Commander component-separation tool has been used to separate the various astrophysical processes in total intensity. Comparison with radio recombination line templates verifies the recovery of the free-free emission along the Galactic plane. Comparison of the high-latitude Hα emission with our free-free map shows residuals that correlate with dust optical depth, consistent with a fraction (≈30%) of Hα having been scattered by high-latitude dust. We highlight a number of diffuse spinning dust morphological features at high latitude. There is substantial spatial variation in the spinning dust spectrum, with the emission peak (in I ν ) ranging from below 20 GHz to more than 50 GHz. There is a strong tendency for the spinning dust component near many prominent H ii regions to have a higher peak frequency, suggesting that this increase in peak frequency is associated with dust in the photo-dissociation regions around the nebulae. The emissivity of spinning dust in these diffuse regions is of the same order as previous detections in the literature. Over the entire sky, the Commander solution finds more anomalous microwave emission (AME) than the WMAP component maps, at the expense of synchrotron and free-free emission. This can be explained by the difficulty in separating multiple broadband components with a limited number of frequency maps. Future surveys, particularly at 5-20 GHz, will greatly improve the separation by constraining the synchrotron spectrum. We combine Planck and WMAP data to make the highest signal-to-noise ratio maps yet of the intensity of the all-sky polarized synchrotron emission at frequencies above a few GHz. Most of the high-latitude polarized emission is associated with distinct large-scale loops and spurs, and we re-discuss their structure. We argue that nearly all the emission at 40 • > l > −90 • is part of the Loop I structure, and show that the emission extends much further in to the southern Galactic hemisphere than previously recognised, giving Loop I an ovoid rather than circular outline. However, it does not continue as far as the "Fermi bubble/microwave haze", making it less probable that these are part of the same structure. We identify a number of new faint features in the polarized sky, including a dearth of polarized synchrotron emission directly correlated with a narrow, roughly 20 • long filament seen in Hα at high Galactic latitude. Finally, we look for evidence of polarized AME, however many AME regions are significantly contaminated by polarized synchrotron emission, and we find a 2σ upper limit of 1.6% in the Perseus region.

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Section: Limits On Ame Polarizationmentioning

confidence: 98%

Planck2015 results

Ade

Aghanim

Alves

et al. 2016

A&A

Self Cite

162

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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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“…Anomalous microwave emission (AME), which is observed at WMAP frequencies shows little polarisation. Dickinson, Peel & Vidal (2011) set upper limits of less than 2.6% on the polarisation of two AME regions (see Rubiño-Martín et al (2012) for a recent review of AME polarisation measurements).…”

Section: Polarised Spectral Indicesmentioning

confidence: 99%

Polarized radio filaments outside the Galactic plane

Vidal

Dickinson

Davies

et al. 2015

Mon. Not. R. Astron. Soc.

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169

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We used data from the WMAP satellite at 23, 33 and 41 GHz to study the diffuse polarised emission over the entire sky. The emission originates mostly from filamentary structures with well-ordered magnetic fields. Some of these structures have been known for decades in radio continuum maps. Their origin is not clear and there are many filaments that are visible for the first time. We have identified and studied 11 filaments. The polarisation fraction of some of them can be as high as 40%, which is a signature of a well ordered magnetic field. The polarisation spectral indices, averaged over 18 regions in the sky is β = −3.06 ± 0.02, consistent with synchrotron radiation. There are significant variations in β over the sky (∆β ≈ 0.2).We explore the link between the large-scale filaments and the local ISM, using the model of an expanding shell in the solar vicinity. We compared observed polarisation angles with the predictions from the model and found good agreement. This strongly suggests that many large scale filaments and loops are nearby structures. This is important in the context of the Galactic magnetic field as these structures are normally included in global models, neglecting the fact that they might be local. We also studied the level of contamination added by the diffuse filaments to the CMB polarisation power spectra. We conclude that, even though these filaments present low radio brightness, a careful removal will be necessary for future all-sky CMB polarisation analysis.

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New constraints on the polarization of anomalous microwave emission in nearby molecular clouds

Cited by 49 publications

References 37 publications

Planck2015 results

Planck2015 results

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

Polarized radio filaments outside the Galactic plane

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