ﻻ يوجد ملخص باللغة العربية
We compute the cross correlation of the intensity and polarisation from the 5-year WMAP data in different sky-regions with respect to template maps for synchrotron, dust, and free-free emission. We derive the frequency dependence and polarisation fraction for all three components in 48 different sky regions of HEALPix (Nside=2) pixelisation. The anomalous emission associated with dust is clearly detected in intensity over the entire sky at the K (23 GHz) and Ka (33 GHz) WMAP bands, and is found to be the dominant foreground at low Galactic latitude, between b=-40 and b=+10. The synchrotron spectral index obtained from the K and Ka WMAP bands from an all-sky analysis is -3.32pm 0.12 for intensity and -3.01pm0.03 for the polarised intensity. The polarisation fraction of the synchrotron is constant in frequency and increases with latitude from ~5% near the Galactic plane up to ~40% in some regions at high latitude; the average value for |b|<20 is 8.6pm1.7 (stat) pm0.5 (sys) % while for |b|>20 it is 19.3pm0.8 (stat) pm 0.5 (sys) %. Anomalous dust and free-free emission appear to be relatively unpolarised...[Abridged]...the average polarisation fraction of dust-correlated emission at K-band is 3.2pm0.9 (stat) pm 1.5 (sys) %, or less than 5% at 95% confidence. When comparing real data with simulations, 8 regions show a detected polarisation above the 99th percentile of the distribution from simulations with no input foreground polarisation, 6 of which are detected at above 2sigma and display polarisation fractions between 2.6% and 7.2%, except for one anomalous region, which has 32pm12%. The dust polarisation values are consistent with the expectation from spinning-dust emission, but polarised dust emission from magnetic-dipole radiation cannot be ruled out. Free-free emission was found to be unpolarised with an upper limit of 3.4% at 95% confidence.
We report limits on the Galactic foreground emission contribution to the Background Emission Anisotropy Scanning Telescope (BEAST) Ka- and Q-band CMB anisotropy maps. We estimate the contribution from the cross-correlations between these maps and the
We present results obtained with the PRONAOS balloon-borne experiment on interstellar dust. In particular, the submillimeter / millimeter spectral index is found to vary between roughly 1 and 2.5 on small scales (3.5 resolution). This could have impl
[Abridged] We present updated estimates of Galactic foreground emission using seven years of WMAP data. Using the power spectrum of differences between multi-frequency template-cleaned maps, we find no evidence for foreground contamination outside of
Experiments designed to measure the redshifted 21~cm line from the Epoch of Reionization (EoR) are challenged by strong astrophysical foreground contamination, ionospheric distortions, complex instrumental response and other different types of noise
We present arcminute-resolution intensity and polarization maps of the Galactic center made with the Atacama Cosmology Telescope (ACT). The maps cover a 32 deg$^2$ field at 98, 150, and 224 GHz with $vert lvertle4^circ$, $vert bvertle2^circ$. We comb