Non-Zeeman Circular Polarization of Molecular Rotational Spectral Lines

Houde, Martin; Hezareh, Talayeh; Jones, Scott C.; Rajabi, Fereshte

doi:10.1088/0004-637x/764/1/24

Cited by 39 publications

(81 citation statements)

References 47 publications

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“…They concluded that the non-Zeeman CO circular polarization is most probably due to a linear-tocircular polarization conversion, consistent with a physical model based on anisotropic resonant scattering of Houde et al (2013). In fact, it is proposed that background, linearly polarized CO emission interacts with similar foreground molecules aligned with the ambient magnetic field and scatters at a transition frequency.…”

Section: Snr Ic 443mentioning

confidence: 52%

A New Look at the Integrated Radio/Microwave Continuum Spectrum of Galactic Supernova Remnant Ic 443

Onić¹,

Urošević²,

Leahy³

2016

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Recent observations of the microwave sky, by the space telescopes such as WMAP and Planck, have opened a new window into the analysis of continuum emission from supernova remnants (SNRs). In this paper, different emission models that can explain the characteristic shape of presently known integrated radio/microwave continuum spectrum of the Galactic SNR IC 443 are tested and discussed. In particular, the possibility that the slight bump in the integrated continuum of this remnant around 20 -70 GHz is genuine and that can be explained by the contribution of additional emission mechanism such as of spinning dust is emphasized. We find that adding a spinning dust component to the emission model improves the fit of the integrated spectrum of this SNR while, at the same time preserves the physically probable parameter values. Finally, models that include the high-frequency synchrotron bending of the IC 443 radio to microwave continuum are favored.

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Section: Snr Ic 443mentioning

confidence: 52%

A New Look at the Integrated Radio/Microwave Continuum Spectrum of Galactic Supernova Remnant Ic 443

Onić¹,

Urošević²,

Leahy³

2016

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“…The emerging photons will acquire a phase shift between their orthogonal scattered components, which causes a transformation of linear into circular polarization. Houde et al (2013) showed that this can readily account for the levels of circular polarization reported in their observations.…”

Section: Introductionmentioning

confidence: 78%

“…Houde et al (2013) reported detecting circular polarization in 12 CO (J = 2 → 1) and HNCO (N Ka Kc = 1 1,12 → 1 1,11 ) in Orion KL and proposed a physical model based on anisotropic resonant scattering in an effort to explain these observations. More precisely, they A&A 558, A45 (2013) showed that when the orientation of the magnetic field changes in the path of the propagation of linearly polarized molecular line radiation, the same species of molecules that emitted this incident background radiation will resonantly scatter them in the foreground at their transition frequency.…”

Section: Introductionmentioning

confidence: 99%

Non-Zeeman circular polarization of CO rotational lines in SNR IC 443

Hezareh

Wiesemeyer

Houde

et al. 2013

A&A

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Context. We study interstellar magnetic fields by measuring the polarization in molecular spectral lines and thermal emission of dust. Aims. We report detection of non-Zeeman circular polarization and linear polarization levels of up to 1% in the 12 CO spectral line emission in a shocked molecular clump around the supernova remnant (SNR) IC 443. We examine our polarization results to confirm that the circular polarization signal in CO lines is caused by a conversion of linear to circular polarization, consistent with anisotropic resonant scattering. In this process background, linearly polarized CO emission interacts with similar foreground molecules aligned with the ambient magnetic field and scatters at a transition frequency. The difference in phase shift between the orthogonally polarized components of this scattered emission can cause a transformation of linear to circular polarization. Methods. We compared linear polarization maps from the dust continuum, which were obtained with PolKa at APEX, and 12 CO (J = 2 → 1) and (J = 1 → 0) from the IRAM 30-m telescope. We found no consistency between the two sets of polarization maps. We then reinserted the measured circular polarization signal in the CO lines across the source to the corresponding linear polarization signal to test whether the linear polarization vectors of the CO maps were aligned with those of the dust before this linear to circular polarization conversion. Results. After the flux correction for the two transitions of the CO spectral lines, the new polarization vectors for both CO transitions aligned with the dust polarization vectors, establishing that the non-Zeeman CO circular polarization is due to a linear to circular polarization conversion.

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“…B-field geometries are generally inferred by preferential emission or absorption by dust or molecules, creating polarized light (e.g., Houde et al 2004Houde et al , 2013Cho & Lazarian 2007). Polarization measurements with molecules require bright lines and are generally restricted to very densesmall-scale structures.…”

Section: Observing Magnetic Fieldsmentioning

confidence: 99%

First Results from BISTRO: A SCUBA-2 Polarimeter Survey of the Gould Belt

Ward-Thompson

Pattle

Bastien

et al. 2017

ApJ

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We present the first results from the B-fields In STar-forming Region Observations (BISTRO) survey, using the Sub-millimetre Common-User Bolometer Array2 camera, with its associated polarimeter (POL-2), on the James Clerk Maxwell Telescope in Hawaii. We discuss the survey's aims and objectives. We describe the rationale behind the survey, and the questions thatthe survey will aim to answer. The most important of these is the role of magnetic fields in the star formation process on the scale of individual filaments and cores in dense regions. We describe the data acquisition and reduction processes for POL-2, demonstrating both repeatability and consistency with previous data. We present a first-look analysis of the first results from the BISTRO survey in the OMC1 region. We see that the magnetic field lies approximately perpendicular to the famous "integral filament" in the densest regions of that filament. Furthermore, we see an "hourglass" magnetic field morphology extending beyond the densest region of the integral filament into the less-dense surrounding material, and discuss possible causes for this. We also discuss the more complex morphology seen along the Orion Bar region. We examine the morphology of the field along the lower-density northeastern filament. We find consistency with previous theoretical models that predict magnetic fields lying parallel to low-density, non-self-gravitating filaments, and perpendicular to higher-density, self-gravitating filaments.

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Non-Zeeman Circular Polarization of Molecular Rotational Spectral Lines

Cited by 39 publications

References 47 publications

A New Look at the Integrated Radio/Microwave Continuum Spectrum of Galactic Supernova Remnant Ic 443

A New Look at the Integrated Radio/Microwave Continuum Spectrum of Galactic Supernova Remnant Ic 443

Non-Zeeman circular polarization of CO rotational lines in SNR IC 443

First Results from BISTRO: A SCUBA-2 Polarimeter Survey of the Gould Belt

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