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

Hezareh, Talayeh; Wiesemeyer, H.; Houde, Martin; Gusdorf, A.; Siringo, G.

doi:10.1051/0004-6361/201321900

Cited by 25 publications

(35 citation statements)

References 42 publications

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“…7 and also with XPOl data from the 30m telescope (Hezareh et al 2013). As expected, the correction is largest at the edges of sources with a nearby strong emission peak, because the Stokes beams P j (j = 1, 2, 3) are usually wider than the antenna power beam pattern P 0 , resulting in an increase of the fractional instrumental polarization.…”

Section: Correction For Instrumental Polarizationsupporting

confidence: 66%

Submillimeter polarimetry with PolKa, a reflection-type modulator for the APEX telescope

Wiesemeyer

Hezareh

Kreysa

et al. 2014

2014 39th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz)

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Imaging polarimetry is an important tool for the study of cosmic magnetic fields. In our Galaxy, polarization levels of a few up to ∼10% are measured in the submillimeter dust emission from molecular clouds and in the synchrotron emission from supernova remnants. Only few techniques exist to image the distribution of polarization angles, as a means of tracing the plane-of-sky projection of the magnetic field orientation. At submillimeter wavelengths, polarization is either measured as the differential total power of polarization-sensitive bolometer elements, or by modulating the polarization of the signal. Bolometer arrays such as LABOCA at the APEX telescope are used to observe the continuum emission from fields as large as ∼ 0.• 2 in diameter. Here we present PolKa, a polarimeter for LABOCA with a reflection-type waveplate of at least 90% efficiency.The modulation efficiency depends mainly on the sampling and on the angular velocity of the waveplate. For the data analysis the concept of generalized synchronous demodulation is introduced. The instrumental polarization towards a point source is at the level of ∼ 0.1%, increasing to a few percent at the −10db contour of the main beam. A method to correct for its effect in observations of extended sources is presented. Our map of the polarized synchrotron emission from the Crab nebula is in agreement with structures observed at radio and optical wavelengths. The linear polarization measured in OMC1 agrees with results from previous studies, while the high sensitivity of LABOCA enables us to also map the polarized emission of the Orion Bar, a prototypical photon-dominated region.

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Section: Correction For Instrumental Polarizationsupporting

confidence: 66%

Submillimeter polarimetry with PolKa, a reflection-type modulator for the APEX telescope

Wiesemeyer

Hezareh

Kreysa

et al. 2014

2014 39th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz)

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“…It is worth mentioning that Hezareh et al (2013) reported detection of non-Zeeman circular polarization and linear polarization levels of up to 1% in the CO rotational spectral line emission in a shocked molecular clump around the SNR IC 443. 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).…”

Section: Snr Ic 443mentioning

confidence: 98%

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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“…A similar technique developed to reduce the leakage effect observed with XPOL instrument from the IRAM 30 m telescope is presented in Hezareh et al (2013). In Fig.…”

Section: Instrumental Polarization and Leakagementioning

confidence: 99%

Polarimetry at millimeter wavelengths with the NIKA camera: calibration and performance

Ritacco

Ponthieu

Catalano

et al. 2017

A&A

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Magnetic fields, which play a major role in a large number of astrophysical processes can be traced via observations of dust polarization. In particular, Planck low-resolution observations of dust polarization have demonstrated that Galactic filamentary structures, where star formation takes place, are associated to well organized magnetic fields. A better understanding of this process requires detailed observations of galactic dust polarization on scales of 0.01 to 0.1 pc. Such high-resolution polarization observations can be carried out at the IRAM 30 m telescope using the recently installed NIKA2 camera, which features two frequency bands at 260 and 150 GHz (respectively 1.15 and 2.05 mm), the 260 GHz band being polarization sensitive. NIKA2 so far in commissioning phase, has its focal plane filled with ∼3300 detectors to cover a Field of View (FoV) of 6.5 arcmin diameter. The NIKA camera, which consisted of two arrays of 132 and 224 Lumped Element Kinetic Inductance Detectors (LEKIDs) and a FWHM (Full-Width-Half-Maximum) of 12 and 18.2 arcsec at 1.15 and 2.05 mm respectively, has been operated at the IRAM 30 m telescope from 2012 to 2015 as a test-bench for NIKA2. NIKA was equipped of a room temperature polarization system (a half wave plate (HWP) and a grid polarizer facing the NIKA cryostat window). The fast and continuous rotation of the HWP permits the quasi simultaneous reconstruction of the three Stokes parameters, I, Q, and U at 150 and 260 GHz. This paper presents the first polarization measurements with KIDs and reports the polarization performance of the NIKA camera and the pertinence of the choice of the polarization setup in the perspective of NIKA2. We describe the polarized data reduction pipeline, specifically developed for this project and how the continuous rotation of the HWP permits to shift the polarized signal far from any low frequency noise. We also present the dedicated algorithm developed to correct systematic leakage effects. We report results on compact and extended sources obtained during the February 2015 technical campaign. These results demonstrate a good understanding of polarization systematics and state-of-the-art performance in terms of photometry, polarization degree and polarization angle reconstruction.

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

Cited by 25 publications

References 42 publications

Submillimeter polarimetry with PolKa, a reflection-type modulator for the APEX telescope

Submillimeter polarimetry with PolKa, a reflection-type modulator for the APEX telescope

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

Polarimetry at millimeter wavelengths with the NIKA camera: calibration and performance

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