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Register a new userSecond and third season QUaD CMB temperature and polarization power spectra
الموجات القوة الحرارية والتوزيع القوة الاستجابة للتشويش للموسمين الثاني والثالث من QUaD CMB
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نحن نقدم نتائج من الموسمين الثاني والثالث من الملاحظات مع تجربة QUaD. تم توليد طيفات القوة المئوية لإشعاع الصوت المجرد من الخلفية الكوكبية لكلا الحرارة والتوزيع المحاكم في كلا 100 غيغاهرتز و150 غيغاهرتز، وكطيفات متصلة بين الترددات. تم تطبيق مجموعة من الاختبارات بالكنجنايف للتحقق من أي اختلالات نظامية محتملة. للحصول على نتائج دقيقة، هذه الاختلالات لم يتم الكشف عنها. نحن نحلل الخريطة الفرقية التي تم تشكيلها بين الحزمتين 100 و150 غيغاهرتز ولا نجد أي دليل على وجود اختلالات أمامية في التوزيع المحاكم. ثم تم دمج الطيفات لتشكيل مجموعة واحدة من النتائج التي تظهر أنها متطابقة مع النموذج المعتاد LCDM. حساسية نتائج التوزيع المحاكم أكثر من أي تجربة سابقة - لأول مرة تم الكشف عن عوامل موسيقية متعددة بشكل معنوي عالي.
We report results from the second and third seasons of observation with the QUaD experiment. Angular power spectra of the Cosmic Microwave Background are derived for both temperature and polarization at both 100 GHz and 150 GHz, and as cross frequency spectra. All spectra are subjected to an extensive set of jackknife tests to probe for possible systematic contamination. For the implemented data cuts and processing technique such contamination is undetectable. We analyze the difference map formed between the 100 and 150 GHz bands and find no evidence of foreground contamination in polarization. The spectra are then combined to form a single set of results which are shown to be consistent with the prevailing LCDM model. The sensitivity of the polarization results is considerably better than that of any previous experiment -- for the first time multiple acoustic peaks are detected in the E-mode power spectrum at high significance.
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QUaD is a bolometric CMB polarimeter sited at the South Pole, operating at frequencies of 100 and 150 GHz. In this paper we report preliminary results from the first season of operation (austral winter 2005). All six CMB power spectra are presented derived as cross spectra between the 100 and 150 GHz maps using 67 days of observation in a low foreground region of approximately 60 square degrees. This data is a small fraction of the data acquired to date. The measured spectra are consistent with the LCDM cosmological model. We perform jackknife tests which indicate that the observed signal has negligible contamination from instrumental systematics. In addition by using a frequency jackknife we find no evidence for foreground contamination.
We present an improved analysis of the final dataset from the QUaD experiment. Using an improved technique to remove ground contamination, we double the effective sky area and hence increase the precision of our CMB power spectrum measurements by ~30% versus that previously reported. In addition, we have improved our modeling of the instrument beams and have reduced our absolute calibration uncertainty from 5% to 3.5% in temperature. The robustness of our results is confirmed through extensive jackknife tests and by way of the agreement we find between our two fully independent analysis pipelines. For the standard 6-parameter LCDM model, the addition of QUaD data marginally improves the constraints on a number of cosmological parameters over those obtained from the WMAP experiment alone. The impact of QUaD data is significantly greater for a model extended to include either a running in the scalar spectral index, or a possible tensor component, or both. Adding both the QUaD data and the results from the ACBAR experiment, the uncertainty in the spectral index running is reduced by ~25% compared to WMAP alone, while the upper limit on the tensor-to-scalar ratio is reduced from r < 0.48 to r < 0.33 (95% c.l). This is the strongest limit on tensors to date from the CMB alone. We also use our polarization measurements to place constraints on parity violating interactions to the surface of last scattering, constraining the energy scale of Lorentz violating interactions to < 1.5 x 10^{-43} GeV (68% c.l.). Finally, we place a robust upper limit on the strength of the lensing B-mode signal. Assuming a single flat band power between l = 200 and l = 2000, we constrain the amplitude of B-modes to be < 0.57 micro-K^2 (95% c.l.).
We constrain parity-violating interactions to the surface of last scattering using spectra from the QUaD experiments second and third seasons of observations by searching for a possible systematic rotation of the polarization directions of CMB photons. We measure the rotation angle due to such a possible cosmological birefringence to be 0.55 deg. +/- 0.82 deg. (random) +/- 0.5 deg. (systematic) using QUaDs 100 and 150 GHz TB and EB spectra over the multipole range 200 < l < 2000, consistent with null, and constrain Lorentz violating interactions to < 2^-43 GeV (68% confidence limit). This is the best constraint to date on electrodynamic parity violation on cosmological scales.
The Chern-Simons term, through which the cosmic Axion-like field couples to the electromagnetic field, has the effect to rotate CMB polarization directions and to break the CPT symmetry. This rotation will change the CMB power spectra, no matter isotropic or anisotropic the rotation angle is. In this paper we revisit this issue by further considering the correlations between the (anisotropic) rotation angle $alpha$ and the CMB temperature and (unrotated) $E$ polarization fields. These correlations could be generated in the Axion-like models with nonzero potential under the adiabatic initial condition. We first investigate how these correlations contribute further modifications to the CMB power spectra, then calculate the CMB bispectra for the temperature and rotated polarization fields. These bispectra would vanish if the $Talpha$ and $Ealpha$ correlations are absent. So, they are useful in searching for CPT violation and the $Talpha$ and $Ealpha$ correlations arisen in the Axion-like models.
In this paper we present a parameter estimation analysis of the polarization and temperature power spectra from the second and third season of observations with the QUaD experiment. QUaD has for the first time detected multiple acoustic peaks in the E-mode polarization spectrum with high significance. Although QUaD-only parameter constraints are not competitive with previous results for the standard 6-parameter LCDM cosmology, they do allow meaningful polarization-only parameter analyses for the first time. In a standard 6-parameter LCDM analysis we find the QUaD TT power spectrum to be in good agreement with previous results. However, the QUaD polarization data shows some tension with LCDM. The origin of this 1 to 2 sigma tension remains unclear, and may point to new physics, residual systematics or simple random chance. We also combine QUaD with the five-year WMAP data set and the SDSS Luminous Red Galaxies 4th data release power spectrum, and extend our analysis to constrain individual isocurvature mode fractions, constraining cold dark matter density, alpha(cdmi)<0.11 (95 % CL), neutrino density, alpha(ndi)<0.26 (95 % CL), and neutrino velocity, alpha(nvi)<0.23 (95 % CL), modes. Our analysis sets a benchmark for future polarization experiments.
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