Far‐Infrared Polarimetry of Galactic Clouds from the Kuiper Airborne Observatory

Dotson, Jessie L.; Davidson, J. A.; Dowell, C. D.; Schleuning, D. A.; Hildebrand, R. H.

doi:10.1086/313384

Cited by 104 publications

(114 citation statements)

References 26 publications

Supporting

Mentioning

102

Contrasting

Order By: Relevance

“…Dotson et al 2000). While this criterion matches no single confidence level, it does fall between the 95% and 99% confidence levels even for low P/σ (Fig.…”

Section: Confidence Regionsmentioning

confidence: 82%

Placing Confidence Limits on Polarization Measurements

Vaillancourt¹

2006

PUBL ASTRON SOC PAC

174

180

View full text Add to dashboard Cite

The determination of the true source polarization given a set of measurements is complicated by the requirement that the polarization always be positive. This positive bias also hinders construction of upper limits, uncertainties, and confidence regions, especially at low signal-to-noise levels. We generate the likelihood function for linear polarization measurements and use it to create confidence regions and upper limits. This is accomplished by integrating the likelihood function over the true polarization (parameter space), rather than the measured polarization (data space). These regions are valid for both low and high signal-to-noise measurements.

show abstract

“…Dotson et al 2000). While this criterion matches no single confidence level, it does fall between the 95% and 99% confidence levels even for low P/σ (Fig.…”

Section: Confidence Regionsmentioning

confidence: 82%

Placing Confidence Limits on Polarization Measurements

Vaillancourt¹

2006

PUBL ASTRON SOC PAC

174

180

View full text Add to dashboard Cite

show abstract

“…The far-IR dust thermal emission being a tracer of the dust mass along the LOS, sensitivity limits explain why detailed dust polarized emission was observed mostly in fairly dense, massive regions of the ISM (Dotson et al 2000;Curran & Chrysostomou 2007;Matthews et al 2009;Dotson et al 2010), in general close to the Galactic plane. Measurements of the more diffuse medium were obtained at relatively low ( 2 • ) angular resolution.…”

Section: Introductionmentioning

confidence: 99%

Planckintermediate results. XIX. An overview of the polarized thermal emission from Galactic dust

Ade¹,

Aghanim²,

Alina³

et al. 2015

A&A

307

View full text Add to dashboard Cite

This paper presents an overview of the polarized sky as seen by Planck HFI at 353 GHz, which is the most sensitive Planck channel for dust polarization. We construct and analyse maps of dust polarization fraction and polarization angle at 1• resolution, taking into account noise bias and possible systematic effects. The sensitivity of the Planck HFI polarization measurements allows for the first time a mapping of Galactic dust polarized emission on large scales, including low column density regions. We find that the maximum observed dust polarization fraction is high (p max = 19.8%), in particular in some regions of moderate hydrogen column density (N H < 2 × 10 21 cm −2 ). The polarization fraction displays a large scatter at N H below a few 10 21 cm −2 . There is a general decrease in the dust polarization fraction with increasing column density above N H 1 × 10 21 cm −2 and in particular a sharp drop above N H 1.5 × 10 22 cm −2 . We characterize the spatial structure of the polarization angle using the angle dispersion function. We find that the polarization angle is ordered over extended areas of several square degrees, separated by filamentary structures of high angle dispersion function. These appear as interfaces where the sky projection of the magnetic field changes abruptly without variations in the column density. The polarization fraction is found to be anti-correlated with the dispersion of polarization angles. These results suggest that, at the resolution of 1• , depolarization is due mainly to fluctuations in the magnetic field orientation along the line of sight, rather than to the loss of grain alignment in shielded regions. We also compare the polarization of thermal dust emission with that of synchrotron measured with Planck, low-frequency radio data, and Faraday rotation measurements toward extragalactic sources. These components bear resemblance along the Galactic plane and in some regions such as the Fan and North Polar Spur regions. The poor match observed in other regions shows, however, that dust, cosmic-ray electrons, and thermal electrons generally sample different parts of the line of sight.

show abstract

“…The polarization measurements in optical (e.g., Vrba et al 1976;Goodman et al 1990;Alves et al 2008;Soam et al 2013;Alves et al 2014), near-infrared (e.g., Goodman et al 1995;Chapman et al 2011;Sugitani et al 2011;Clemens 2012;Cashman & Clemens 2014;Bertrang et al 2014;Kusune et al 2015;Alves et al 2014) and submillimeter-millimeter wavelengths (e.g., Rao et al 1998;Dotson et al 2000Dotson et al , 2010Vaillancourt & Matthews 2012;Hull et al 2014;Alves et al 2014) are used to map the magnetic field geometry of molecular clouds. Optical polarization position angles trace the plane of the sky orientation of the ambient magnetic field at the periphery of the molecular clouds (with A V ∼ 1-2 mag; Goodman et al 1995;Goodman 1996).…”

Section: Introductionmentioning

confidence: 99%

Magnetic field geometry of an unusual cometary cloud Gal 110-13

Neha

Maheswar

Soam

et al. 2016

A&A

View full text Add to dashboard Cite

Aims. We carried out optical polarimetry of an isolated cloud, Gal 110-13, to map the plane-of-the-sky magnetic field geometry. The main aim of the study is to understand the most plausible mechanism responsible for the unusual cometary shape of the cloud in the context of its magnetic field geometry. Methods. When unpolarized starlight passes through the intervening interstellar dust grains that are aligned with their short axes parallel to the local magnetic field, it gets linearly polarized. The plane-of-the-sky magnetic field component can therefore be traced by doing polarization measurements of background stars projected on clouds. Because the light in the optical wavelength range is most efficiently polarized by the dust grains typically found in the outer layers of the molecular clouds, optical polarimetry enables us to trace the magnetic field geometry of the outer layers of the clouds. Results. We made R-band polarization measurements of 207 stars in the direction of Gal 110-13. The distance of Gal 110-13 was determined as ∼450 ± 80 pc using our polarization and 2MASS near-infrared data. The foreground interstellar contribution was removed from the observed polarization values by observing a number of stars located in the vicinity of Gal 110-13 which has Hipparcos parallax measurements. The plane-of-the-sky magnetic field lines are found to be well ordered and aligned with the elongated structure of Gal 110-13. Using structure function analysis, we estimated the strength of the plane-of-the-sky component of the magnetic field as ∼25 μG. Conclusions. Based on our results and comparing them with those from simulations, we conclude that compression by the ionization fronts from 10 Lac is the most plausible cause of the comet-like morphology of Gal 110-13 and of the initiation of subsequent star formation.

show abstract

Far‐Infrared Polarimetry of Galactic Clouds from the Kuiper Airborne Observatory

Cited by 104 publications

References 26 publications

Placing Confidence Limits on Polarization Measurements

Placing Confidence Limits on Polarization Measurements

Planckintermediate results. XIX. An overview of the polarized thermal emission from Galactic dust

Magnetic field geometry of an unusual cometary cloud Gal 110-13

Contact Info

Product

Resources

About