A new approach for a Galactic synchrotron polarized emission template in the microwave range

Bernardi, G.; Carretti, E.; Fabbri, R.; Sbarra, C.; Poppi, S.; Cortiglioni, S.

doi:10.1046/j.1365-8711.2003.06898.x

Cited by 12 publications

(14 citation statements)

References 31 publications

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“…Measurements of starlight polarization serve as a template for the analysis of polarized microwave dust emission (Fosalba et al 2002;Bernardi et al 2003). We have combined several catalogs of optical dust polarization measurements (Heiles 2000;Berdyugin et al , 2004Berdyugin & Teerikorpi 2002) to construct a template for the magnetic field direction in dusty environments.…”

Section: Starlight Polarization and Polarized Dust Emissionmentioning

confidence: 99%

Three‐Year Wilkinson Microwave Anisotropy Probe ( WMAP ) Observations: Polarization Analysis

Page

Hinshaw

Komatsu

et al. 2007

ASTROPHYS J SUPPL S

834

616

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The Wilkinson Microwave Anisotropy Probe (WMAP) has mapped the entire sky in five frequency bands between 23 and 94 GHz with polarization-sensitive radiometers. We present 3 year full-sky maps of the polarization and analyze them for foreground emission and cosmological implications. These observations open up a new window for understanding how the universe began and help set a foundation for future observations. WMAP observes significant levels of polarized foreground emission due to both Galactic synchrotron radiation and thermal dust emission. Synchrotron radiation is the dominant signal at l < 50 and P 40 GHz, while thermal dust emission is evident at 94 GHz. The least contaminated channel is at 61 GHz. We present a model of polarized foreground emission that captures the large angular scale characteristics of the microwave sky. After applying a Galactic mask that cuts 25.7% of the sky, we show that the high Galactic latitude rms polarized foreground emission, averaged over l ¼ 4Y6, ranges from %5 K at 22 GHz to P0.6 K at 61 GHz. By comparison, the levels of intrinsic CMB polarization for a ÃCDM model with an optical depth of ¼ 0:09 and assumed tensor-to-scalar ratio r ¼ 0:3 are %0.3 K for E-mode polarization and %0.1 K for B-mode polarization. To analyze the maps for CMB polarization at l < 16, we subtract a model of the foreground emission that is based primarily on a scaling WMAP's 23 GHz map. In the foregroundcorrected maps, we detect l(l þ 1)C EE l¼ 2Y6 h i /2 ¼ 0:086 AE 0:029 (K) 2 . This is interpreted as the result of rescattering of the CMB by free electrons released during reionization at z r ¼ 10:9 þ2:7 À2:3 for a model with instantaneous reionization. By computing the likelihood of just the EE data as a function of we find ¼ 0:10 AE 0:03. When the same EE data are used in the full six-parameter fit to all WMAP data ( TT, TE, EE), we find ¼ 0:09 AE 0:03. Marginalization over the foreground subtraction affects this value by < 0:01. We see no evidence for B modes, limiting them to l(l þ 1)C BB l¼ 2Y6 h i /2 ¼ À0:04 AE 0:03 (K) 2 . We perform a template fit to the E-mode and B-mode data with an approximate model for the tensor scalar ratio. We find that the limit from the polarization signals alone is r < 2:2 (95% CL), where r is evaluated at k ¼ 0:002 Mpc À1 . This corresponds to a limit on the cosmic density of gravitational waves of GW h 2 < 5 ; 10 À12 . From the full WMAP analysis, we find r < 0:55 (95% CL) corresponding to a limit of GW h 2 < 1 ; 10 À12 (95% CL). The limit on r is approaching the upper bound of predictions for some of the simplest models of inflation, r $ 0:3. Subject headingg s: cosmic microwave background -cosmology: observations -polarization Online material: color figure

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Section: Starlight Polarization and Polarized Dust Emissionmentioning

confidence: 99%

Three‐Year Wilkinson Microwave Anisotropy Probe ( WMAP ) Observations: Polarization Analysis

Page

Hinshaw

Komatsu

et al. 2007

ASTROPHYS J SUPPL S

834

616

View full text Add to dashboard Cite

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“…The synchrotron emission from our Galaxy is the major foreground contamination, which has been modeled by various groups (e.g. Bernardi et al 2003). The DRAO 1.4 GHz polarization survey of the northern sky (Wolleben et al 2006), our 4.8 GHz survey and the Wilkinson Microwave Anisotropy Probe (WMAP) polarization data (Page et al 2006) might be combined to yield a detailed template.…”

Section: Introductionmentioning

confidence: 99%

A Sino-German $\mathsf{\lambda}$6 cm polarization survey of the Galactic plane

Sun

Han

Reich

et al. 2006

A&A

139

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Aims. Polarization measurements of the Galactic plane at λ6 cm probe the interstellar medium (ISM) to larger distances compared to measurements at longer wavelengths, enabling us to investigate properties of the Galactic magnetic fields and electron density. Methods. We are conducting a new λ6 cm continuum and polarization survey of the Galactic plane covering 10• ≤ l ≤ 230• and |b| ≤ 5• . Missing large-scale structures in the U and Q maps are restored based on extrapolated polarization K-band maps from the WMAP satellite. The λ6 cm data are analyzed together with maps in other bands. Results. We discuss some results for the first survey region, 7• × 10 • in size, centered at (l, b) = (125.• 5, 0 • ). Two new passive Faraday screens, G125.6−1.8 and G124.9+0.1, were detected. They cause significant rotation of background polarization angles but little depolarization. G124.9+0.1 was identified as a new faint HII region at a distance of 2.8 kpc. G125.6−1.8, with a size of about 46 pc, has neither a counterpart in enhanced Hα emission nor in total intensity. A model combining foreground and background polarization modulated by the Faraday screen was developed. Using this model, we estimated the strength of the ordered magnetic field along the line of sight to be 3.9 µG for G124.9+0.1, and exceeding 6.4 µG for G125.6−1.8. We obtained an estimate of 2.5 and 6.3 mK kpcfor the average polarized and total synchrotron emissivity towards G124.9+0.1. The synchrotron emission beyond the Perseus arm is quite weak. A spectral curvature previously reported for SNR G126.2+1.6 is ruled out by our new data, which prove a straight spectrum. Conclusions. The new λ6 cm survey will play an important role in improving the understanding of the properties of the magnetoionic ISM. The magnetic fields in HII regions can be measured. Faraday screens with very low electron densities but large rotation measures were detected indicating strong and regular magnetic fields in the ISM. Information about the local synchrotron emissivity can be obtained.Key words. surveys -polarization -radio continuum: general -methods: observational -ISM: magnetic fields -ISM: supernova remnants IntroductionThe first detection of diffuse polarized emission from the Milky Way Galaxy (Westerhout et al. 1962;Wielebinski et al. 1962) confirmed that its non-thermal radiation originates from synchrotron emission. The two major sources of polarized emission from our Galaxy are diffuse radio emission associated with the Galactic disk produced by relativistic electrons spiraling in interstellar magnetic fields, and discrete sources such as supernova remnants (SNRs) with compressed interstellar magnetic fields, where relativistic electrons are accelerated by shocks.To understand the properties of the ISM in our Galaxy a number of whole sky surveys (e.g. as reviewed by Reich 2003) have been made. Also large-scale radio surveys of the Galactic plane with higher angular resolution have been performed. The large-scale surveys clearly show the concentration of emission ...

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“…The last step, which assumes an essentially common location for dust selective absorption of starlight and for synchrotron emission, is of crucial importance. Several tests discussed by Bernardi et al (2003) support the reliability of the template under this respect, and in connection with the polarization horizon modelling for Π as well. Due to the Heiles data sampling the template has been provided for an angular scale of 7…”

Section: A Synchrotron Template At Sport Scalesmentioning

confidence: 59%

“…Giardino et al (2002) use D97, the total-intensity survey of Haslam et al (1981) and other radio data to produce a real-space model of polarized synchrotron emission T and Π; the polarization angle however is just taken as a random quantity, so the final synthetic maps were declared to be a toy model. A more powerful approach has been recently introduced by Bernardi et al (2003), intended to produce a Faraday-free template of polarized synchrotron. It is based on the following steps: (a) A synchrotron intensity map is built using the 408 MHz total intensity survey of Haslam et al (1981) and the 1.4 GHz survey of Reich & Reich (1986).…”

Section: A Synchrotron Template At Sport Scalesmentioning

confidence: 99%

“…APS computed on Faraday-free templates can be extrapolated to higher frequencies better than those of current surveys. Due to the low resolution, results could be provided by Bernardi et al (2003) only for l ≤ 20, where the full-map template gives α P = 1.9 ± 0.2 and α Π = 1.9 ± 0.2. The substantial agreement with surveys at 2.4-2.7 GHz reinforces both the validity of the template and our previous support to moderate spectral slopes.…”

Section: A Synchrotron Template At Sport Scalesmentioning

confidence: 99%

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