Linear polarization measurements of extragalactic radio  
 sources at <i>λ</i>6.3 cm

Zukowski, Edwin L. H.; Kronberg, P. P.; Forkert, T.; Wielebinski, R.

doi:10.1051/aas:1999190

Cited by 8 publications

(4 citation statements)

References 3 publications

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“…This is consistent, when extrapolated to lower flux densities, with a result from the CBI experiment valid in the range 5-50 mJy (Mason et al 2002). The distribution of point source polarization fractions at 5 GHz can be characterized by an exponential with a mean of 3.8% (Zukowski et al 1999); data of somewhat lower quality at 15 GHz are consistent with the same distribution (Simard-Normandin, Kronberg, & Neidhoefer 1981b). Qualitatively one expects the polarization fraction of synchrotrondominated sources to initially rise with frequency, and then plateau or fall, with the break point at frequencies ≪ 5 GHz (see Simard-Normandin, Kronberg, & Button (1981a) for an example).…”

Section: Point Sourcesmentioning

confidence: 99%

Detection of polarization in the cosmic microwave background using DASI

Kovac

Leitch

Pryke

et al. 2002

Nature

585

543

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We report the detection of polarized anisotropy in the Cosmic Microwave Background radiation with the Degree Angular Scale Interferometer (DASI), located at the Amundsen-Scott South Pole research station. Observations in all four Stokes parameters were obtained within two 34 FWHM fields separated by one hour in Right Ascension. The fields were selected from the subset of fields observed with DASI in 2000 in which no point sources were detected and are located in regions of low Galactic synchrotron and dust emission. The temperature angular power spectrum is consistent with previous measurements and its measured frequency spectral index is −0.01 (−0.16 -0.14 at 68% confidence), where 0 corresponds to a 2.73 K Planck spectrum. The power spectrum of the detected polarization is consistent with theoretical predictions based on the interpretation of CMB anisotropy as arising from primordial scalar adiabatic fluctuations. Specifically, E-mode polarization is detected at high confidence (4.9σ). Assuming a shape for the power spectrum consistent with previous temperature measurements, the level found for the E-mode polarization is 0.80 (0.56 -1.10), where the predicted level given previous temperature data is 0.9 -1.1. At 95% confidence, an upper limit of 0.59 is set to the level of B-mode polarization with the same shape and normalization as the E-mode spectrum. The T E correlation of the temperature and E-mode polarization is detected at 95% confidence, and also found to be consistent with predictions. These results provide strong validation of the underlying theoretical framework for the origin of CMB anisotropy and lend confidence to the values of the cosmological parameters that have been derived from CMB measurements.

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Section: Point Sourcesmentioning

confidence: 99%

Detection of polarization in the cosmic microwave background using DASI

Kovac

Leitch

Pryke

et al. 2002

Nature

585

543

View full text Add to dashboard Cite

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“…No evidence of jets is seen in any of the VLA images. The core is quite prominent, containing 475 mJy (Rudnick et al 1986) at 5 GHz compared to the integrated flux density of 970 mJy (Gregory & Condon 1991;Zukowski et al 1999). We chose to observe 3C 166, primarily based on the relatively high fractional polarization of the core of 1.7% (8 mJy of polarized flux density) at 5 GHz (Rudnick et al 1986).…”

Section: C 166mentioning

confidence: 99%

Very Long Baseline Array Polarimetry of Three Powerful Radio Galaxy Cores

Taylor

Hough

Venturi

2001

ApJ

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We present sensitive, high dynamic range, Very Long Baseline Array (VLBA) polarimetric observations of the cores of three powerful radio galaxies: 3C 166, 3C 236 and 3C 390.3. Significant polarization is detected in one source (3C 166) allowing us to map out the Faraday Rotation Measure (RM) distribution and projected magnetic field direction. The inner jet of 3C 166 is found to have a rest frame RM of −2300 rad m −2 , similar to those found in quasars cores. No polarized flux was detected from the other two sources, but in both counterjets are seen. The counterjet in 3C 236 was previously known, but the detection in 3C 390.3 is a new discovery. We suggest that the low fractional polarization in radio galaxy cores is the result of Faraday depolarization by ionized gas associated with the accretion disk. The lower polarization of radio galaxy cores compared to quasars is then naturally explained by unified models as a result of the viewing angle.

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“…Faraday rotation is the classic method of probing large-scale magnetic fields in the universe, using quasars as sources of polarized radiation, e.g. [24]. Faraday rotation of radiation from discrete point sources can constrain the primordial magnetic field power spectrum [25], and can also probe the evolution of the magnetic field with redshift [26].…”

Section: Introductionmentioning

confidence: 99%

Faraday rotation of the cosmic microwave background polarization by a stochastic magnetic field

et al. 2005

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A primordial cosmological magnetic field induces Faraday rotation of the cosmic microwave background polarization. This rotation produces a curl-type polarization component even when the unrotated polarization possesses only gradient-type polarization, as expected from scalar density perturbations. We compute the angular power spectrum of curl-type polarization arising from small Faraday rotation due to a weak stochastic primordial magnetic field with a power-law power spectrum. The induced polarization power spectrum peaks at arcminute angular scales. Faraday rotation is one of the few cosmological sources of curl-type polarization, along with primordial tensor perturbations, gravitational lensing, and the vector and tensor perturbations induced by magnetic fields; the Faraday rotation signal peaks on significantly smaller angular scales than any of these, with a power spectrum amplitude which can be comparable to that from gravitational lensing. Prospects for detection are briefly discussed.

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Linear polarization measurements of extragalactic radio sources at λ6.3 cm

Cited by 8 publications

References 3 publications

Detection of polarization in the cosmic microwave background using DASI

Detection of polarization in the cosmic microwave background using DASI

Very Long Baseline Array Polarimetry of Three Powerful Radio Galaxy Cores

Faraday rotation of the cosmic microwave background polarization by a stochastic magnetic field

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