Antenna instrumental polarization and its effects on <i>E</i>- and <i>B</i>-modes for CMBP observations

Carretti, E.; Cortiglioni, S.; Sbarra, C.; Tascone, R.

doi:10.1051/0004-6361:20035601

Cited by 21 publications

(25 citation statements)

References 18 publications

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“…The plots show the typical butterfly pattern (e.g. see Gregorini et al 1992, Carretti et al 2004, O'Dea et al 2007). The off-axis instrumental polarization level compared to the Stokes I peak is 0.3%.…”

Section: Polarization Calibrationmentioning

confidence: 91%

Sardinia Radio Telescope wide-band spectral-polarimetric observations of the galaxy cluster 3C 129

Murgia

Govoni

Carretti

et al. 2016

Mon. Not. R. Astron. Soc.

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We present new observations of the galaxy cluster 3C 129 obtained with the Sardinia Radio Telescope in the frequency range 6000−7200 MHz, with the aim to image the large-angular-scale emission at high-frequency of the radio sources located in this cluster of galaxies. The data were acquired using the recently-commissioned ROACH2-based backend to produce full-Stokes image cubes of an area of 1 o ×1 o centered on the radio source 3C 129. We modeled and deconvolved the telescope beam pattern from the data. We also measured the instrumental polarization beam patterns to correct the polarization images for off-axis instrumental polarization. Total intensity images at an angular resolution of 2.9 ′ were obtained for the tailed radio galaxy 3C 129 and for 13 more sources in the field, including 3C 129.1 at the galaxy cluster center. These data were used, in combination with literature data at lower frequencies, to derive the variation of the synchrotron spectrum of 3C 129 along the tail of the radio source. If the magnetic field is at the equipartition value, we showed that the lifetimes of radiating electrons result in a radiative age for 3C 129 of t syn ≃ 267 ± 26 Myrs. Assuming a linear projected length of 488 kpc for the tail, we deduced that 3C 129 is moving supersonically with a Mach number of M = v gal /c s = 1.47. Linearly polarized emission was clearly detected for both 3C 129 and 3C 129.1. The linear polarization measured for 3C 129 reaches levels as high as 70% in the faintest region of the source where the magnetic field is aligned with the direction of the tail.

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Section: Polarization Calibrationmentioning

confidence: 91%

Sardinia Radio Telescope wide-band spectral-polarimetric observations of the galaxy cluster 3C 129

Murgia

Govoni

Carretti

et al. 2016

Mon. Not. R. Astron. Soc.

Self Cite

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“…Furthermore, there are no reflections from optical surfaces to induce spurious instrumental polarization, an unavoidable problem for any system with imaging optics 26,27,28,29 . In MBI there are no aberrations from off-axis pixels: all feed elements are equivalent and all the optics are at cryogenic temperatures to minimize losses.…”

Section: Control Of Systematic Effectsmentioning

confidence: 99%

The millimeter-wave bolometric interferometer

et al. 2006

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The Millimeter-Wave Bolometric Interferometer (MBI) is designed for sensitive measurements of the polarization of the cosmic microwave background (CMB). MBI combines the differencing capabilities of an interferometer with the high sensitivity of bolometers at millimeter wavelengths. It views the sky directly through corrugated horn antennas with low sidelobes and nearly symmetric beam patterns to avoid spurious instrumental polarization from reflective optics. The design of the first version of the instrument with four 7-degree-FOV corrugated horns (MBI-4) is discussed. The MBI-4 optical band is defined by filters with a central frequency of 90 GHz. The set of baselines determined by the antenna separation makes the instrument sensitive to CMB polarization fluctuations over the multipole range l=150-270. In MBI-4, the signals from antennas are combined with a Fizeau beam combiner and interference fringes are detected by an array of spider-web bolometers with NTD germanium thermistors. In order to separate the visibility signals from the total power detected by each bolometer, the phase of the signal from each antenna is modulated by a ferrite-based waveguide phase shifter. Observations are planned from the Pine Bluff Observatory outside Madison, WI.

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“…The systematic effects due to axisymmetric beams have been assessed by Carretti et al (2004) and a completely general assessment of the asymmetries by O'Dea et al (2007). The map-making method described in this paper provides a mechanism to account and correct for arbitrary beam asymmetries, hence the term deconvolution map-making.…”

Section: Introductionmentioning

confidence: 99%

A deconvolution map-making method for experiments with circular scanning strategies

Harrison

Leeuwen

Ashdown³

2011

A&A

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Aims. We investigate the performance of a deconvolution map-making algorithm for an experiment with a circular scanning strategy, specifically in this case for the analysis of Planck data, and we quantify the effects of making maps using simplified approximations to the true beams. Methods. We present an implementation of a map-making algorithm which allows the combined treatment of temperature and polarisation data, and removal of instrumental effects, such as detector time constants and finite sampling intervals, as well as the deconvolution of arbitrarily complex beams from the maps. This method may be applied to any experiment with a circular scanningstrategy.Results. Low-resolution experiments were used to demonstrate the ability of this method to remove the effects of arbitrary beams from the maps and to demonstrate the effects on the maps of ignoring beam asymmetries. Additionally, results are presented of an analysis of a realistic full-scale simulated data-set for the Planck LFI 30 GHz channel. Conclusions. Our method successfully removes the effects of the beams from the maps, and although it is computationally expensive, the analysis of the Planck LFI data should be feasible with this approach.

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Antenna instrumental polarization and its effects on E- and B-modes for CMBP observations

Cited by 21 publications

References 18 publications

Sardinia Radio Telescope wide-band spectral-polarimetric observations of the galaxy cluster 3C 129

Sardinia Radio Telescope wide-band spectral-polarimetric observations of the galaxy cluster 3C 129

The millimeter-wave bolometric interferometer

A deconvolution map-making method for experiments with circular scanning strategies

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