CMB B -mode non-Gaussianity:Optimal bispectrum estimator and Fisher forecasts

Upcoming cosmic microwave background (CMB) data can be used to explore harmonic 3-point functions that involve the B-mode component of the CMB polarization signal. We focus on bispectra describing the non-Gaussian correlation of the B-mode field and the CMB temperature anisotropies (T) and/or E-mode polarization, i.e. , , and . Such bispectra probe violations of the tensor consistency relation: the model-independent behavior of cosmological correlation functions that involve a large-wavelength tensor mode (gravitational wave). An observed violation of the tensor consistency relation would exclude a large number of inflation models. We describe a generalization of the Komatsu-Spergel-Wandelt (KSW) bispectrum estimator that allows statistical inference on this type of primordial non-Gaussianity with data of the CMB temperature and polarization anisotropies. The generalized estimator shares its statistical properties with the existing KSW estimator and retains the favorable numerical scaling with angular resolution. In this paper we derive the estimator and present a set of Fisher forecasts. We show how the forecasts scale with various experimental parameters such as lower and upper angular band-limit, relevant for e.g. the upcoming ground-based Simons Observatory experiment and proposed LiteBIRD satellite experiment. We comment on possible contaminants due to secondary cosmological and astrophysical sources.Comment: 40 pages, 7 figure

Modelling ground pickup for microwave telescopes

Microwave telescopes require an ever-increasing control of experimental systematics in their quest to measure the Cosmic Microwave Background (CMB) to exquisite levels of precision. One important systematic for ground and balloon-borne experiments is ground pickup, where beam sidelobes detect the thermal emission of the much warmer ground while the main beam is scanning the sky. This generates scan-synchronous noise in experiment timestreams, which is difficult to filter out without also deleting some of the signal from the sky. Therefore, efficient modelling of pickup can help guide the design of experiments and of analysis pipelines. In this work, we present an extension to the beamconv algorithm that enables us to generate time-ordered data (TOD) from beam-convolved sky and ground maps simultaneously. We simulate ground pickup for both a ground-based experiment and a telescope attached to a stratospheric balloon. Ground templates for the balloon experiment are obtained by re-projecting satellite maps of the Earth's microwave emission.Comment: 10 pages, 6 figures, paper 12190-165 for the "SPIE AT+I 2022 mm, sub-mmm, and Far-Infrared Detectors and Instrumentation for Astronomy XI" conferenc

The effectiveness of a training for patients with unexplained physical symptoms: protocol of a cognitive behavioral group training and randomized controlled trial

Abstract: BACKGROUND: In primary care, up to 74% of physical symptoms is classified as unexplained. These symptoms can cause high levels of distress and healthcare utilization. Cognitive behavioral therapy has shown to be effective, but does not seem to be attractive to patients. An exception herein is a therapy based on the consequences model, which distinguishes itself by its labeling of psychosocial distress in terms of consequences rather than as causes of physical symptoms. In secondary care, 81% of the patients accepts this therapy, but in primary care the outcome is poor. We assume that positive outcome can also be reached in primary care, when the consequences model is modified and used bottom-up in an easily accessible group training, in which patients are relieved of being blamed for their symptoms. Our aim is to investigate the (cost-)effectiveness of this training. METHODS AND DESIGN: A randomized controlled trial is designed. One hundred patients are randomized to either the group training or the waiting list. Physicians in general practices and outpatients clinics of general hospitals refer patients. Referral leads to inclusion if patients are between 18 and 65 years old, understand Dutch, have no handicaps impeding participation and the principal DSM-IV-TR classification is undifferentiated somatoform disorder or chronic pain disorder. In contrast to other treatment effect studies, the co-morbidity of a personality disorder does not lead to exclusion. By this, we optimize the comparability between the study population and patients in daily practice enlarging the generalization possibilities. Also in contrast to other effect studies, we chose quality of life (SF-36) instead of physical symptoms as the primary outcome measure. The SF-6D is used to estimate Quality Adjusted Life Years (QALYs). Costs are measured with the Trimbos/iMTA Questionnaire for Costs associated with Psychiatric Illness. Measurements are scheduled at baseline, after the training or waiting list, three and twelve months after the training. The differences between measurements are analyzed according to the intention-to-treat principle. The cost-effectiveness is expressed as costs per QALY, using multiple sensitivity analyses on the basis of a probabilistic model of the trial. DISCUSSION: If we show that our group training is (cost-)effective, more patients could be served, their quality of life could be improved while costs might be reduced. As the training is investigated in a heterogeneous patient group i

Minimizing gravitational lensing contributions to the primordial bispectrum covariance

The next generation of ground-based cosmic microwave background (CMB) experiments aim to measure temperature and polarization fluctuations up to ℓmax≈5000 over half of the sky. Combined with Planck data on large scales, this will provide improved constraints on primordial non-Gaussianity. However, the impressive resolution of these experiments will come at a price. Besides signal confusion from galactic foregrounds, extragalactic foregrounds, and late-time gravitational effects, gravitational lensing will introduce large non-Gaussianity that can become the leading contribution to the bispectrum covariance through the connected four-point function. Here, we compute this effect analytically for the first time on the full sky for both temperature and polarization. We compare our analytical results with those obtained directly from map-based simulations of the CMB sky for several levels of instrumental noise. Of the standard shapes considered in the literature, the local shape is most affected, resulting in a 35% increase of the estimator standard deviation for an experiment such as the Simons Observatory (SO) and a 110% increase for a cosmic-variance limited experiment, including both temperature and polarization modes up to ℓmax=3800. Because of the nature of the lensing four-point function, the impact on other shapes is reduced while still non-negligible for the orthogonal shape. Two possible avenues to reduce the non-Gaussian contribution to the covariance are proposed: First by marginalizing over lensing contributions, such as the Integrated Sachs Wolfe (ISW)-lensing three-point function in temperature, and second by delensing the CMB. We show the latter method can remove almost all extra covariance, reducing the effect to below <5% for local bispectra. At the same time, delensing would remove signal biases from secondaries induced by lensing, such as ISW lensing. We aim to apply both techniques directly to the forthcoming SO data when searching for primordial non-Gaussianity

The Atacama Cosmology Telescope: Galactic Dust Structure and the Cosmic PAH Background in Cross-correlation with WISE

We present a cross-correlation analysis between $1'$ resolution total intensity and polarization observations from the Atacama Cosmology Telescope (ACT) at 150 and 220 GHz and 15$''$ mid-infrared photometry from the Wide-field Infrared Survey Explorer (WISE) over 107 12.5$^\circ\times$12.5$^\circ$ patches of sky. We detect a spatially isotropic signal in the WISE$\times$ACT $TT$ cross power spectrum at 30$\sigma$ significance that we interpret as the correlation between the cosmic infrared background at ACT frequencies and polycyclic aromatic hydrocarbon (PAH) emission from galaxies in WISE, i.e., the cosmic PAH background. Within the Milky Way, the Galactic dust $TT$ spectra are generally well-described by power laws in $\ell$ over the range 10$^3 < \ell <$10$^4$, but there is evidence both for variability in the power law index and for non-power law behavior in some regions. We measure a positive correlation between WISE total intensity and ACT $E$-mode polarization at 1000$< \ell \lesssim$6000 at $>$3$\sigma$ in each of 35 distinct $\sim$100 deg$^2$ regions of the sky, suggesting alignment between Galactic density structures and the local magnetic field persists to sub-parsec physical scales in these regions. The distribution of $TE$ amplitudes in this $\ell$ range across all 107 regions is biased to positive values, while there is no evidence for such a bias in the $TB$ spectra. This work constitutes the highest-$\ell$ measurements of the Galactic dust $TE$ spectrum to date and indicates that cross-correlation with high-resolution mid-infrared measurements of dust emission is a promising tool for constraining the spatial statistics of dust emission at millimeter wavelengths.Comment: 20 pages, 14 figures, submitted to Ap

The Atacama Cosmology Telescope: Detection of mm-wave transient sources

We report on the serendipitous discovery of three transient mm-wave sources using data from the Atacama Cosmology Telescope. The first, detected at RA = 273.8138, dec = -49.4628 at ${\sim}50\sigma$ total, brightened from less than 5 mJy to at least 1100 mJy at 150 GHz with an unknown rise time shorter than thirteen days, during which the increase from 250 mJy to 1100 mJy took only 8 minutes. Maximum flux was observed on 2019-11-8. The source's spectral index in flux between 90 and 150 GHz was positive, $\alpha = 1.5\pm0.2$. The second, detected at RA = 105.1584, dec = -11.2434 at ${\sim}20\sigma$ total, brightened from less than 20 mJy to at least 300 mJy at 150 GHz with an unknown rise time shorter than eight days. Maximum flux was observed on 2019-12-15. Its spectral index was also positive, $\alpha = 1.8\pm0.2$. The third, detected at RA = 301.9952, dec = 16.1652 at ${\sim}40\sigma$ total, brightened from less than 8 mJy to at least 300 mJy at 150 GHz over a day or less but decayed over a few days. Maximum flux was observed on 2018-9-11. Its spectrum was approximately flat, with a spectral index of $\alpha = -0.2\pm0.1$. None of the sources were polarized to the limits of these measurements. The two rising-spectrum sources are coincident in position with M and K stars, while the third is coincident with a G star.Comment: 8 pages, 4 figures, 1 tabl

The Simons Observatory: Beam characterization for the Small Aperture Telescopes

We use time-domain simulations of Jupiter observations to test and develop a beam reconstruction pipeline for the Simons Observatory Small Aperture Telescopes. The method relies on a map maker that estimates and subtracts correlated atmospheric noise and a beam fitting code designed to compensate for the bias caused by the map maker. We test our reconstruction performance for four different frequency bands against various algorithmic parameters, atmospheric conditions and input beams. We additionally show the reconstruction quality as function of the number of available observations and investigate how different calibration strategies affect the beam uncertainty. For all of the cases considered, we find good agreement between the fitted results and the input beam model within a ~1.5% error for a multipole range l = 30 - 700.Comment: 22 pages, 21 figures, to be submitted to Ap

The Atacama Cosmology Telescope: Cosmology from cross-correlations of unWISE galaxies and ACT DR6 CMB lensing

We present tomographic measurements of structure growth using cross-correlations of Atacama Cosmology Telescope (ACT) DR6 and Planck CMB lensing maps with the unWISE Blue and Green galaxy samples, which span the redshift ranges $0.2 \lesssim z \lesssim 1.1$ and $0.3 \lesssim z \lesssim 1.8$, respectively. We improve on prior unWISE cross-correlations not just by making use of the new, high-precision ACT DR6 lensing maps, but also by including additional spectroscopic data for redshift calibration and by analysing our measurements with a more flexible theoretical model. An extensive suite of systematic and null tests within a blind analysis framework ensures that our results are robust. We determine the amplitude of matter fluctuations at low redshifts ($z\simeq 0.2-1.6$), finding $S_8 \equiv \sigma_8 (\Omega_m / 0.3)^{0.5} = 0.813 \pm 0.021$ using the ACT cross-correlation alone and $S_8 = 0.810 \pm 0.015$ with a combination of Planck and ACT cross-correlations; these measurements are fully consistent with the predictions from primary CMB measurements assuming standard structure growth. The addition of Baryon Acoustic Oscillation data breaks the degeneracy between $\sigma_8$ and $\Omega_m$, allowing us to measure $\sigma_8 = 0.813 \pm 0.020$ from the cross-correlation of unWISE with ACT and $\sigma_8 = 0.813\pm 0.015$ from the combination of cross-correlations with ACT and Planck. These results also agree with the expectations from primary CMB extrapolations in $\Lambda$CDM cosmology; the consistency of $\sigma_8$ derived from our two redshift samples at $z \sim 0.6$ and $1.1$ provides a further check of our cosmological model. Our results suggest that structure formation on linear scales is well described by $\Lambda$CDM even down to low redshifts $z\lesssim 1$.Comment: 73 pages (incl. 30 pages of appendices), 50 figures, 16 tables, to be submitted to ApJ. Watch G. S. Farren and A. Krolewski discuss the analysis and results under https://cosmologytalks.com/2023/09/11/act-unwis