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One of the most important checks for systematic errors in CMB studies is the cross correlation of maps made by independent experiments. In this paper we report on the cross correlation between maps from the Atacama B-mode Search (ABS) and Atacama Cosmology Telescope (ACT) experiments in both temperature and polarization. These completely different measurements have a clear correlation with each other and with the Planck satellite in both the EE and TE spectra at $ell<400$ over the roughly $1100$ deg$^2$ common to all three. The TB, EB, and BB cross spectra are consistent with noise. Exploiting such cross-correlations will be important for future experiments operating in Chile that aim to probe the $30<ell<8,000$ range.
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In this study, we apply the Analytical method of Blind Separation (ABS) of the cosmic microwave background (CMB) from foregrounds to estimate the CMB temperature power spectrum from multi-frequency microwave maps. We test the robustness of the ABS estimator and assess the accuracy of the power spectrum recovery by using realistic simulations based on the seven-frequency Planck data, including various frequency-dependent and spatially-varying foreground components (synchrotron, free-free, thermal dust and anomalous microwave emission), as well as an uncorrelated Gaussian-distributed instrumental noise. Considering no prior information about the foregrounds, the ABS estimator can analytically recover the CMB power spectrum over almost all scales with less than $0.5%$ error for maps where the Galactic plane region ($|b|<10^{circ}$) is masked out. To further test the flexibility and effectiveness of the ABS approach in a variety of situations, we apply the ABS to the simulated Planck maps in three cases: (1) without any mask, (2) imposing a two-times-stronger synchrotron emission and (3) including only the Galactic plane region ($|b|<10^{circ}$) in the analysis. In such extreme cases, the ABS approach can still provide an unbiased estimate of band powers at the level of 1 $murm{K}^2$ on average over all $ell$ range, and the recovered powers are consistent with the input values within 1-$sigma$ for most $ell$ bins.
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 present the joint analysis of Neutral Hydrogen (HI) Intensity Mapping observations with three galaxy samples: the Luminous Red Galaxy (LRG) and Emission Line Galaxy (ELG) samples from the eBOSS survey, and the WiggleZ Dark Energy Survey sample. The HI intensity maps are Green Bank Telescope observations of the redshifted 21cm emission on 100deg2 covering the redshift range $0.6<z<1.0$. We process the data by separating and removing the foregrounds with FastICA, and construct a transfer function to correct for the effects of foreground removal on the HI signal. We cross-correlate the cleaned HI data with the galaxy samples and study the overall amplitude as well as the scale-dependence of the power spectrum. We also qualitatively compare our findings with the predictions by a semi-analytic galaxy evolution simulation. The cross-correlations constrain the quantity $Omega_{{HI}} b_{{HI}} r_{{HI},{opt}}$ at an effective scale $k_{eff}$, where $Omega_{HI}$ is the HI density fraction, $b_{HI}$ is the HI bias, and $r_{{HI},{opt}}$ the galaxy-hydrogen correlation coefficient, which is dependent on the HI content of the optical galaxy sample. At $k_{eff}=0.31 , h/{Mpc}$ we find $Omega_{{HI}} b_{{HI}} r_{{HI},{Wig}} = [0.58 pm 0.09 , {(stat) pm 0.05 , {(sys)}}] times 10^{-3}$ for GBT-WiggleZ, $Omega_{{HI}} b_{{HI}} r_{{HI,{ELG}}} = [0.40 pm 0.09 , {(stat) pm 0.04 , {(sys)}}] times 10^{-3}$ for GBT-ELG, and $Omega_{{HI}} b_{{HI}} r_{{HI},{LRG}} = [0.35 pm 0.08 , {(stat) pm 0.03 , {(sys)}}] times 10^{-3}$ for GBT-LRG, at $zsimeq 0.8$. We also report results at $k_{eff}=0.24 , h/{Mpc}$ and $k_{eff}=0.48 , h/{Mpc}$. With little information on HI parameters beyond our local Universe, these are amongst the most precise constraints on neutral hydrogen density fluctuations in an underexplored redshift range.
The Atacama Cosmology Telescope (ACT) is currently observing the cosmic microwave background with arcminute resolution at 148 GHz, 218 GHz, and 277 GHz. In this paper, we present ACTs first results. Data have been analyzed using a maximum-likelihood map-making method which uses B-splines to model and remove the atmospheric signal. It has been used to make high-precision beam maps from which we determine the experiments window functions. This beam information directly impacts all subsequent analyses of the data. We also used the method to map a sample of galaxy clusters via the Sunyaev-Zeldovich (SZ) effect, and show five clusters previously detected with X-ray or SZ observations. We provide integrated Compton-y measurements for each cluster. Of particular interest is our detection of the z = 0.44 component of A3128 and our current non-detection of the low-redshift part, providing strong evidence that the further cluster is more massive as suggested by X-ray measurements. This is a compelling example of the redshift-independent mass selection of the SZ effect.
We present a tomographic measurement of the cross-correlation between thermal Sunyaev-Zeldovich (tSZ) maps from ${it Planck}$ and the Atacama Cosmology Telescope (ACT) and weak galaxy lensing shears measured during the first three years of observations of the Dark Energy Survey (DES Y3). This correlation is sensitive to the thermal energy in baryons over a wide redshift range, and is therefore a powerful probe of astrophysical feedback. We detect the correlation at a statistical significance of $21sigma$, the highest significance to date. We examine the tSZ maps for potential contaminants, including cosmic infrared background (CIB) and radio sources, finding that CIB has a substantial impact on our measurements and must be taken into account in our analysis. We use the cross-correlation measurements to test different feedback models. In particular, we model the tSZ using several different pressure profile models calibrated against hydrodynamical simulations. Our analysis marginalises over redshift uncertainties, shear calibration biases, and intrinsic alignment effects. We also marginalise over $Omega_{rm m}$ and $sigma_8$ using ${it Planck}$ or DES priors. We find that the data prefers the model with a low amplitude of the pressure profile at small scales, compatible with a scenario with strong AGN feedback and ejection of gas from the inner part of the halos. When using a more flexible model for the shear profile, constraints are weaker, and the data cannot discriminate between different baryonic prescriptions.
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