Average fractional polarization of extragalactic sources at <i>Planck</i> frequencies

Trombetti, T.; Burigana, C.; Zotti, G. de; Galluzzi, Vincenzo; Massardi, M.

doi:10.1051/0004-6361/201732342

Cited by 21 publications

(35 citation statements)

References 50 publications

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“…These results are consistent with the conclusion by Bonavera et al [127] who applied stacking techniques to radio sources detected by Planck in total intensity, finding an average fractional polarization of 3%, essentially independent of frequency from 30 to 353 GHz. A similar conclusion was reached by the independent analysis of Trombetti et al [128].…”

Section: Detecting Sources In Polarizationsupporting

confidence: 81%

“…These low values of Π are understood as due to the complex structure of galactic magnetic fields, with reversals along the line of sight, and to the disordered alignment of dust grains; both effects work to decrease the global polarization degree. Nevertheless, the current limits on the distribution of polarization fractions of dusty galaxies permit a contamination of CMB polarization maps comparable to that of radio sources down to 100-140 GHz, and dominant at higher frequencies [131,128]. The amplitude of the power spectrum of polarized dusty galaxies may be close to the level of CMB lensing B-modes and of primordial B-modes for r 0.01.…”

Section: Detecting Sources In Polarizationmentioning

confidence: 91%

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Extragalactic Astrophysics With Next-Generation CMB Experiments

Zotti

Bonato

Negrello

et al. 2019

Front. Astron. Space Sci.

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Planck, SPT and ACT surveys have clearly demonstrated that Cosmic Microwave Background (CMB) experiments, while optimised for cosmological measurements, have made important contributions to the field of extragalactic astrophysics in the last decade. Future CMB experiments have the potential to make even greater contributions. One example is the detection of highz galaxies with extreme gravitational amplifications. The combination of flux boosting and of stretching of the images has allowed the investigation of the structure of galaxies at z 3 with the astounding spatial resolution of about 60 pc. Another example is the detection of proto-clusters of dusty galaxies at high z when they may not yet possess the hot intergalactic medium allowing their detection in X-rays or via the Sunyaev-Zeldovich effect. Next generation CMB experiments, like PICO, CORE, CMB-Bharat from space and Simons Observatory and CMB-S4 from the ground, will discover several thousands of strongly lensed galaxies out to z ∼ 6 or more and of 1 arXiv:1907.05323v1 [astro-ph.GA] 11 Jul 2019 De Zotti et al. Running Title Figure 1. Effect of angular resolution on the confusion limit. The filled blue circles show the differential counts of sources on SPT maps degraded to the PICO resolution at 150 GHz (FWHM = 6.2 ; left panel) and 220 GHz (FWHM = 3.6 ; right panel) compared with the SPT counts of Mocanu et al. [5, orange stars]. The vertical dot-dashed lines correspond, from left to right, to the 90% completeness limits at the full SPT resolution, at the PICO resolution and at the Planck resolution.galaxy proto-clusters caught in the phase when their member galaxies where forming the bulk of their stars. They will also detect tens of thousands of local dusty galaxies and thousands of radio sources at least up to z 5. Moreover they will measure the polarized emission of thousands of radio sources and of dusty galaxies at mm/sub-mm wavelengths.

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Section: Detecting Sources In Polarizationsupporting

confidence: 81%

Section: Detecting Sources In Polarizationmentioning

confidence: 91%

Extragalactic Astrophysics With Next-Generation CMB Experiments

Zotti

Bonato

Negrello

et al. 2019

Front. Astron. Space Sci.

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“…The results shown in Table 1 are consistent with previous studies of AGN and DSFGs. Briefly, in previous studies, polarisation fraction is found to be independent of flux (Battye et al 2011;Trombetti et al 2018;Datta et al 2018) and frequency (Battye et al 2011;Galluzzi et al 2017 Weighted Mean 6 − 1500 686 6.9 ± 1.1 2.63 ± 0.22 Table 1. Mean-squared polarisation fractions ( p 2 ) and inferred fractional polarisation ( p 2 ) measurements for Nsource number of SPT-SZ selected sources stacked in flux bins Srange using 95 and 150 GHz SPTpol maps.…”

Section: Comparison To Previous Resultsmentioning

confidence: 89%

“…GHz frequencies, and overall mean p is estimated at a level around 1 − 5 per cent, which are all consistent with our findings in this work. For comparison, we show the squared values of polarisation fraction p 2 from Bonavera et al (2017a) and Trombetti et al (2018) (at 100 and 143 GHz Planck frequencies) in both panels of Fig 3. In the right panel, we also show p 2 measured by Datta et al (2018) at 148 GHz ACTpol observing frequency. On the dusty side, Bonavera et al (2017b) used Planck data to study ∼ 4700 dusty sources selected at 857 GHz with S ≥ 791 mJy (a flux threshold that is comparable to this work when extrapolated to 150 GHz).…”

Section: Comparison To Previous Resultsmentioning

confidence: 99%

“…In recent years, we have seen the first measurements of the polarisation properties of AGN at CMB frequencies, although these measurements have been restricted to the brightest AGN. Using data from the Planck satellite, Bonavera et al (2017a) found p = 2.9 +0.3 −0.5 per cent and Trombetti et al (2018) found p = 3.06 ± 0.28 per cent at 143 GHz for sources above 1 Jy and 525 mJy, respectively. An analysis of Atacama Cosmology Telescope (ACTpol) data found a consistent p = 2.8 ± 0.5 per cent for sources brighter than 215 mJy at 148 GHz (Datta et al 2018).…”

Section: Introductionmentioning

confidence: 99%

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Fractional polarization of extragalactic sources in the 500 deg2 SPTpol survey

Gupta

Reichardt

Ade

et al. 2019

Monthly Notices of the Royal Astronomical Society

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We study the polarisation properties of extragalactic sources at 95 and 150 GHz in the SPTpol 500 deg 2 survey. We estimate the polarised power by stacking maps at known source positions, and correct for noise bias by subtracting the mean polarised power at random positions in the maps. We show that the method is unbiased using a set of simulated maps with similar noise properties to the real SPTpol maps. We find a flux-weighted mean-squared polarisation fraction p 2 = [8.9 ± 1.1] × 10 −4 at 95 GHz and [6.9 ± 1.1] × 10 −4 at 150 GHz for the full sample. This is consistent with the values obtained for a sub-sample of active galactic nuclei. For dusty sources, we find 95 per cent upper limits of p 2 95 < 16.9 × 10 −3 and p 2 150 < 2.6 × 10 −3 . We find no evidence that the polarisation fraction depends on the source flux or observing frequency. The 1-σ upper limit on measured mean squared polarisation fraction at 150 GHz implies that extragalactic foregrounds will be subdominant to the CMB E and B mode polarisation power spectra out to at least 5700 ( 4700) and 5300 ( 3600), respectively at 95 (150) GHz.

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Impact of polarised extragalactic sources on the measurement of CMBB-mode anisotropies

Lagache

Béthermin

Montier

et al. 2020

A&A

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One of the main goals of cosmology is to search for the imprint of primordial gravitational waves in the polarisation filed of the cosmic microwave background to probe inflation theories. One of the obstacles in detecting the primordial signal is that the cosmic microwave background B-mode polarisation must be extracted from among astrophysical contaminations. Most efforts have focus on limiting Galactic foreground residuals, but extragalactic foregrounds cannot be ignored at the large scale (ℓ ≲ 150), where the primordial B-modes are the brightest. We present a complete analysis of extragalactic foreground contamination that is due to polarised emission of radio and dusty star-forming galaxies. We update or use current models that are validated using the most recent measurements of source number counts, shot noise, and cosmic infrared background power spectra. We predict the flux limit (confusion noise) for future cosmic microwave background (CMB) space-based or balloon-borne experiments (IDS, PIPER, SPIDER, LiteBIRD, and PICO), as well as ground-based experiments (C-BASS, NEXT-BASS, QUIJOTE, AdvACTPOL, BICEP3+Keck, BICEPArray, CLASS, Simons Observatory, SPT3G, and S4). The telescope aperture size (and frequency) is the main characteristic that affects the level of confusion noise. Using the flux limits and assuming mean polarisation fractions independent of flux and frequency for radio and dusty galaxies, we computed the B-mode power spectra of the three extragalactic foregrounds (radio source shot noise, dusty galaxy shot noise, and clustering). We discuss their relative levels and compare their amplitudes to that of the primordial tensor modes parametrised by the tensor-to-scalar ratio r. At the reionisation bump (ℓ = 5), contamination by extragalactic foregrounds is negligible. While the contamination is much lower than the targeted sensitivity on r for large-aperture telescopes at the recombination peak (ℓ = 80), it is at a comparable level for some of the medium- (∼1.5 m) and small-aperture telescope (≤0.6 m) experiments. For example, the contamination is at the level of the 68% confidence level uncertainty on the primordial r for the LiteBIRD and PICO space-based experiments. These results were obtained in the absence of multi-frequency component separation (i.e. considering each frequency independently). We stress that extragalactic foreground contaminations have to be included in the input sky models of component separation methods dedicated to the recovery of the CMB primordial B-mode power spectrum. Finally, we also provide some useful unit conversion factors and give some predictions for the SPICA B-BOP experiment, which is dedicated to Galactic and extragalactic polarisation studies. We show that SPICA B-BOP will be limited at 200 and 350 μm by confusion from extragalactic sources for long integrations in polarisation, but very short integrations in intensity.

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Average fractional polarization of extragalactic sources at Planck frequencies

Cited by 21 publications

References 50 publications

Extragalactic Astrophysics With Next-Generation CMB Experiments

Extragalactic Astrophysics With Next-Generation CMB Experiments

Fractional polarization of extragalactic sources in the 500 deg2 SPTpol survey

Impact of polarised extragalactic sources on the measurement of CMBB-mode anisotropies

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