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Tensions in cosmological parameters measurement motivate a revisit of the effects of instrumental systematics. In this article, we focus on the Pearsons correlation coefficient of the cosmic microwave background temperature and polarization E modes $mathcal{R}_ell^{rm TE}$ which has the property of not being biased by multiplicative instrumental systematics. We build a $mathcal{R}_ell^{rm TE}$-based likelihood for the Planck data, and present the first constraints on $Lambda$CDM parameters from the correlation coefficient. Our results are compatible with parameters derived from a power spectra based likelihood. In particular the value of the Hubble parameter $H_0$ characterizing the expansion of the Universe today, 67.5 $pm$ 1.3 km/s/Mpc, is consistent with the ones inferred from standard CMB analysis. We also discuss the consistency of the Planck correlation coefficient with the one computed from the most recent ACTPol power spectra.
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Testing deviations from the $Lambda$CDM model using the Cosmic Microwave Background (CMB) power spectra requires a pristine understanding of instrumental systematics. In this work we discuss the properties of a new observable ${cal R}^{TE}_{ell}$, the correlation coefficient of temperature and E modes. We find that this observable is mostly unaffected by systematics introducing multiplicative biases such as errors in calibration, polarisation efficiency, beam and transfer function measurements. We discuss the dependency of this observable on the cosmological model and derive its statistical properties. We then compute the T-E correlation coefficients of Planck legacy data and compare them with expectations from the Planck best-fit $Lambda$CDM and foreground model.
We present the temperature power spectrum of the Cosmic Microwave Background obtained by cross-correlating maps from the Atacama Cosmology Telescope (ACT) at 148 and 218 GHz with maps from the Planck satellite at 143 and 217 GHz, in two overlapping regions covering 592 square degrees. We find excellent agreement between the two datasets at both frequencies, quantified using the variance of the residuals between the ACT power spectra and the ACTxPlanck cross-spectra. We use these cross-correlations to calibrate the ACT data at 148 and 218 GHz, to 0.7% and 2% precision respectively. We find no evidence for anisotropy in the calibration parameter. We compare the Planck 353 GHz power spectrum with the measured amplitudes of dust and cosmic infrared background (CIB) of ACT data at 148 and 218 GHz. We also compare planet and point source measurements from the two experiments.
We demonstrate that the cosmic microwave background (CMB) temperature-polarization cross-correlation provides accurate and robust constraints on cosmological parameters. We compare them with the results from temperature or polarization and investigate the impact of foregrounds, cosmic variance, and instrumental noise. This analysis makes use of the Planck high-multipole HiLLiPOP likelihood based on angular power spectra, which takes into account systematics from the instrument and foreground residuals directly modelled using Planck measurements. The temperature-polarization correlation (TE) spectrum is less contaminated by astrophysical emissions than the temperature power spectrum (TT), allowing constraints that are less sensitive to foreground uncertainties to be derived. For {Lambda}CDM parameters, TE gives very competitive results compared to TT. For basic {Lambda}CDM model extensions (such as AL, {Sigma}m{ u}, or Neff ), it is still limited by the instrumental noise level in the polarization maps.
We show that the f(T) gravitational paradigm, in which gravity is described by an arbitrary function of the torsion scalar, can provide a mechanism for realizing bouncing cosmologies, thereby avoiding the Big Bang singularity. After constructing the simplest version of an f(T) matter bounce, we investigate the scalar and tensor modes of cosmological perturbations. Our results show that metric perturbations in the scalar sector lead to a background-dependent sound speed, which is a distinguishable feature from Einstein gravity. Additionally, we obtain a scale-invariant primordial power spectrum, which is consistent with cosmological observations, but suffers from the problem of a large tensor-to-scalar ratio. However, this can be avoided by introducing extra fields, such as a matter bounce curvaton.
We measure the cross-correlation between galaxy groups constructed from DESI Legacy Imaging Survey DR8 and Planck CMB lensing, over overlapping sky area of 16876 $rm deg^2$. The detections are significant and consistent with the expected signal of the large scale structure of the universe, over group samples of various redshift, mass and richness $N_{rm g}$ and over various scale cuts. The overall S/N is 39 for a conservative sample with $N_{rm g}geq 5$, and increases to $48$ for the sample with $N_{rm g}geq 2$. Adopting the Planck 2018 cosmology, we constrain the density bias of groups with $N_{rm g}geq 5$ as $b_{rm g}=1.31pm 0.10$, $2.22pm 0.10$, $3.52pm 0.20$ at $0.1<zleq 0.33$, $0.33<zleq 0.67$, $0.67<zleq1$ respectively. The value-added group catalog allows us to detect the dependence of bias on group mass with high significance. It also allows us to compare the measured bias with the theoretically predicted one using the estimated group mass. We find excellent agreement for the two high redshift bins. However, it is lower than the theory by $sim 3sigma$ for the lowest redshift bin. Another interesting finding is the significant impact of the thermal Sunyaev Zeldovich (tSZ). It contaminates the galaxy group-CMB lensing cross-correlation at $sim 30%$ level, and must be deprojected first in CMB lensing reconstruction.
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