Exploring Cosmic Origins with CORE: Cosmological Parameters

We forecast the main cosmological parameter constraints achievable with theCORE space mission which is dedicated to mapping the polarisation of the CosmicMicrowave Background (CMB). CORE was recently submitted in response to ESA'sfifth call for medium-sized mission proposals (M5). Here we report the resultsfrom our pre-submission study of the impact of various instrumental options, inparticular the telescope size and sensitivity level, and review the great,transformative potential of the mission as proposed. Specifically, we assessthe impact on a broad range of fundamental parameters of our Universe as afunction of the expected CMB characteristics, with other papers in the seriesfocusing on controlling astrophysical and instrumental residual systematics. Inthis paper, we assume that only a few central CORE frequency channels areusable for our purpose, all others being devoted to the cleaning ofastrophysical contaminants. On the theoretical side, we assume LCDM as ourgeneral framework and quantify the improvement provided by CORE over thecurrent constraints from the Planck 2015 release. We also study the jointsensitivity of CORE and of future Baryon Acoustic Oscillation and Large ScaleStructure experiments like DESI and Euclid. Specific constraints on the physicsof inflation are presented in another paper of the series. In addition to thesix parameters of the base LCDM, which describe the matter content of aspatially flat universe with adiabatic and scalar primordial fluctuations frominflation, we derive the precision achievable on parameters like thosedescribing curvature, neutrino physics, extra light relics, primordial heliumabundance, dark matter annihilation, recombination physics, variation offundamental constants, dark energy, modified gravity, reionization and cosmicbirefringence. (ABRIDGED

The anterior temporal lobes are critically involved in acquiring new conceptual knowledge:evidence for impaired feature integration in semantic dementia

AbstractRecent evidence from multiple neuroscience techniques indicates that regions within the anterior temporal lobes (ATLs) are a critical node in the neural network for representing conceptual knowledge, yet their function remains elusive. The hub-and-spoke model holds that ATL regions act as a transmodal conceptual hub, distilling the various sensory-motor features of objects and words into integrated, coherent conceptual representations. Single-cell recordings in monkeys suggest that the ATLs are critically involved in visual associative learning; however, investigations of this region in humans have focused on existing knowledge rather than learning. We studied acquisition of new concepts in semantic dementia patients, who have cortical damage centred on the ventrolateral aspects of the ATLs. Patients learned to assign abstract visual stimuli to two categories. The categories conformed to a family resemblance structure in which no individual stimulus features were fully diagnostic; thus the task required participants to form representations that integrate multiple features into a single concept. Patients were unable to do this, instead responding only on the basis of individual features. The study reveals that integrating disparate sources of information into novel coherent concepts is a critical computational function of the ATLs. This explains the central role of this region in conceptual representation and the catastrophic breakdown of concepts in semantic dementia

Planck intermediate results X. Physics of the hot gas in the Coma cluster

We present an analysis of Planck satellite data on the Coma cluster observed via the Sunyaev-Zeldovich effect. Thanks to its great sensitivity, Planck is able, for the first time, to detect SZ emission up to r ≈ 3 × R500. We test previously proposed spherically symmetric models for the pressure distribution in clusters against the azimuthally averaged data. In particular, we find that the Arnaud et al. (2010, A&A, 517, A92) "universal" pressure profile does not fit Coma, and that their pressure profile for merging systems provides a reasonable fit to the data only at r R500 than the mean pressure profile predicted by the simulations used to constrain the models. The Planck image shows significant local steepening of the y profile in two regions about half a degree to the west and to the south-east of the cluster centre. These features are consistent with the presence of shock fronts at these radii, and indeed the western feature was previously noticed in the ROSAT PSPC mosaic as well as in the radio. Using Plancky profiles extracted from corresponding sectors we find pressure jumps of 4.9-0.2+0.4 and 5.0-0.1+1.3 in the west and south-east, respectively. Assuming Rankine-Hugoniot pressure jump conditions, we deduce that the shock waves should propagate with Mach number Mw = 2.03-0.04+0.09 and Mse = 2.05-0.02+0.25 in the west and south-east, respectively. Finally, we find that the y and radio-synchrotron signals are quasi-linearly correlated on Mpc scales, with small intrinsic scatter. This implies either that the energy density of cosmic-ray electrons is relatively constant throughout the cluster, or that the magnetic fields fall off much more slowly with radius than previously thought. © 2013 ESO

Cosmology with the SZ spectrum: Measuring the Universe’s temperature with galaxy clusters

The hot gas in clusters of galaxies creates a distinctive spectral distortion in the cosmic microwave background (CMB) via the Sunyaev-Zel’dovich (SZ) effect. The spectral signature of the SZ can be used to measure the CMB temperature at cluster redshift (TCMB(z)) and to constrain the monopole of the y-type spectral distortion of the CMB spectrum. In this work, we start showing the measurements of TCMB(z) for a sample extracted from the Second Catalog of galaxy clusters produced by Planck (PSZ2) and containing 75 clusters selected from CHEX-MATE. Then we show the forecasts for future CMB experiments about the constraints on the monopole of the y-type spectral distortion of the CMB spectrum via the spectrum of the SZ effect

S-Z constraints on the dependence of the CMB temperature on redshift

Precise measurements of the Sunyaev–Zel’dovich (S–Z) effect on clusters of galaxies can be used to constrain anomalous scalings of the CMB temperature as a function of redshift, providing an unbiased test of the current cosmological paradigms. This is possible through a precise characterization of the S–Z spectrum as a function of frequency and all the higher order effects which determine small corrections to the amplitude of the effect. Combined with excellent systematic modeling and high quality, routine observations of the S–Z effect on a moderate-to-high redshift sample of galaxy clusters at millimeter and submillimeter wavelengths, this method can constrain deviations from standard scalings of the CMB temperature based on zero-redshift precisions comparable with that of COBE/FIRAS. We describe here the analysis procedure and a pioneering approach to the problem using existing multifrequency S–Z observations

SZ Observations with MITO: 2 MAD, the multi-pixel photometer

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Sunyaev-Zel’dovich effect at supercluster scales with Planck

A significant fraction of the baryons in the low redshift Universe is expected to be in a warm-hot phase (WHIM) with temperatures of the order of 105-107 K, and with moderate overdensities δ ∼ 10-100 (Cen & Ostriker 1999). This WHIM would be associated to a network of filaments connecting the regions where clusters of galaxies are located. In this work, we have explored the possibility of detecting this WHIM phase with PLANCK, by means of the Sunyaev-Zel'dovich effect (SZE) associated to regions containing superclusters. We have used hydrodynamic simulations including the gas physics, to identify those regions which are similar to present-day superclusters. Six maps of the Comptonization parameter (y) at PLANCK resolution have been prepared from these regions centered in a supercluster. For their analysis, we have excluded those regions in the maps which are associated to identified clusters in the simulation, studying only the SZ signal produced by the remaining gas in the supercluster. We find that the most intense features in these proccesed maps are produced by small haloes (clumps in the simulations which are not identified as clusters), although these clumps are part of filaments. PLANCK should be able to detect at least one intense feature (y > 8 × 10-6) not associated to a cluster for every 8 superclusters. The probability of observing those features is a strong function of the elongation of the supercluster along the line of sight, so detections are most probable in highly elongated superclusters. © Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence