Astrophysical foregrounds and primordial tensor-to-scalar ratio constraints from CMB B-mode polarization observations

We study the effects of astrophysical foregrounds on the ability of CMB B-mode polarization experiments to constrain the primordial tensor-to-scalar ratio, r. To clean the foreground contributions we use parametric, maximum likelihood component separation technique, and consider experimental setups optimized to render a minimal level of the foreground residuals in the recovered CMB map. We consider nearly full-sky observations, include two diffuse foreground components, dust and synchrotron, and study cases with and without calibration errors, spatial variability of the foreground properties, and partial or complete B-mode lensing signal removal. In all these cases we find that in the limit of very low noise level and in the absence of the intrumental or modeling systematic effects, the foreground residuals do not lead to a limit on the lowest detectable value of r. But the need to control the foreground residuals will play a major role in determining the minimal noise levels necessary to permit a robust detection of r < 0.1 and therefore in optimizing and forecasting the performance of the future missions. For current and proposed experiments noise levels, the foreground residuals are found non-negligible and potentially can affect our ability to set constraints on r. We also show how the constraints can be significantly improved on by restricting the post component separation processing to a smaller sky area. This procedure applied to a case of a COrE-like satellite mission is shown to result potentially in over an order of magnitude improvement in the detectable value of r. With sufficient knowledge of the experimental bandpasses as well as foreground component scaling laws, our conclusions are found to be independent on the assumed overall normalization of the foregrounds and only quantitatively depend on specific parametrizations assumed for the foreground components.Comment: 5 pages, 2 figure

Veille sociologique et flux d'informations numériques: Une expérience de chronique automatique sur les thèmes sanitaires et environnementaux

Depuis plus d'une dizaine d'années, les travaux de sociologie sur les alertes et les controverses publiques se sont accompagnés de développements informatiques spécifiques. Le principal objectif de ces travaux est d'outiller les enquêtes, en permettant de lier le suivi de grands dossiers, notamment des dossiers sanitaires, environnementaux ou technologiques (amiante, nucléaire, OGM, nanotechnologies, pesticides, champs électro-magnétiques), et la modélisation des formes de l'action et du jugement utilisées par de multiples protagonistes. Il ne s'agit pas de développer une sociologie des discours ou des textes mais bien de considérer les ensembles discursifs comme des lieux de cristallisation de processus sociaux complexes marqués par une profonde réflexivité des acteurs, puisque ceux qui s'imposent sont aussi ceux qui concentrent le plus d'expertise - ou de contre-expertise - sur les dossiers en question . Dans le cadre de ces travaux, pour faire face à l'accumulation documentaire et aux changements de phases, comme lorsque se produit un emballement politique ou médiatique sur un sujet, il est décisif de disposer de protocoles de " veille ". La fonction de ces protocoles est d'assurer dans le même mouvement la mise à jour des bases documentaires et l'identification des changements de régimes argumentatifs, l'émergence de nouveaux acteurs ou d'événements et de prises de parole susceptibles de modifier les éléments centraux d'un dossier

Robust forecasts on fundamental physics from the foreground-obscured, gravitationally-lensed CMB polarization

[Abridged] Recent results from the BICEP, Keck Array and Planck Collaborations demonstrate that Galactic foregrounds are an unavoidable obstacle in the search for evidence of inflationary gravitational waves in the cosmic microwave background (CMB) polarization. Beyond the foregrounds, the effect of lensing by intervening large-scale structure further obscures all but the strongest inflationary signals permitted by current data. With a plethora of ongoing and upcoming experiments aiming to measure these signatures, careful and self-consistent consideration of experiments' foreground- and lensing-removal capabilities is critical in obtaining credible forecasts of their performance. We investigate the capabilities of instruments such as Advanced ACTPol, BICEP3 and Keck Array, CLASS, EBEX10K, PIPER, Simons Array, SPT-3G and SPIDER, and projects as COrE+, LiteBIRD-ext, PIXIE and Stage IV, to clean contamination due to polarized synchrotron and dust from raw multi-frequency data, and remove lensing from the resulting co-added CMB maps (either using iterative CMB-only techniques or through cross-correlation with external data). Incorporating these effects, we present forecasts for the constraining power of these experiments in terms of inflationary physics, the neutrino sector, and dark energy parameters. Made publicly available through an online interface, this tool enables the next generation of CMB experiments to foreground-proof their designs, optimize their frequency coverage to maximize scientific output, and determine where cross-experimental collaboration would be most beneficial. We find that analyzing data from ground, balloon and space instruments in complementary combinations can significantly improve component separation performance, delensing, and cosmological constraints over individual datasets.Comment: 37 pages plus appendices, 15 figures; first two authors contributed equally to this work; forecasting tool available at http://turkey.lbl.gov. v4: matches version published in JCAP (with extended dark energy constraints

Concert recording 2019-10-15

[Track 1]. Sonata for viola and piano, op. 11. I. Adagio [Track 2]. II. Quasi menuetto, tranquillo - Sempre motto e sciolto [Track 3]. III. Allegro risoluto e vivace / Hans Gal -- [Track 4]. Pieces de viole, Livre 4. Rondeau - L\u27Agreable [Track 5]. La Provencale [Track 6]. La Matelotte [Track 7]. Le Basque / Marin Marais -- [Track 8]. Sonata for viola and piano Arpeggione D. 821. Allegro moderato [Track 9]. Adagio Allegretto / Franz Schubert

Acoustical structured illumination for super-resolution ultrasound imaging.

Structured illumination microscopy is an optical method to increase the spatial resolution of wide-field fluorescence imaging beyond the diffraction limit by applying a spatially structured illumination light. Here, we extend this concept to facilitate super-resolution ultrasound imaging by manipulating the transmitted sound field to encode the high spatial frequencies into the observed image through aliasing. Post processing is applied to precisely shift the spectral components to their proper positions in k-space and effectively double the spatial resolution of the reconstructed image compared to one-way focusing. The method has broad application, including the detection of small lesions for early cancer diagnosis, improving the detection of the borders of organs and tumors, and enhancing visualization of vascular features. The method can be implemented with conventional ultrasound systems, without the need for additional components. The resulting image enhancement is demonstrated with both test objects and ex vivo rat metacarpals and phalanges

Ultrasound localization microscopy to image and assess microvasculature in a rat kidney.

The recent development of ultrasound localization microscopy, where individual microbubbles (contrast agents) are detected and tracked within the vasculature, provides new opportunities for imaging the vasculature of entire organs with a spatial resolution below the diffraction limit. In stationary tissue, recent studies have demonstrated a theoretical resolution on the order of microns. In this work, single microbubbles were localized in vivo in a rat kidney using a dedicated high frame rate imaging sequence. Organ motion was tracked by assuming rigid motion (translation and rotation) and appropriate correction was applied. In contrast to previous work, coherence-based non-linear phase inversion processing was used to reject tissue echoes while maintaining echoes from very slowly moving microbubbles. Blood velocity in the small vessels was estimated by tracking microbubbles, demonstrating the potential of this technique to improve vascular characterization. Previous optical studies of microbubbles in vessels of approximately 20 microns have shown that expansion is constrained, suggesting that microbubble echoes would be difficult to detect in such regions. We therefore utilized the echoes from individual MBs as microscopic sensors of slow flow associated with such vessels and demonstrate that highly correlated, wideband echoes are detected from individual microbubbles in vessels with flow rates below 2 mm/s

Characterising cosmic birefringence in the presence of galactic foregrounds and instrumental systematic effects

We study a possibility of constraining isotropic cosmic birefringence with help of cosmic microwave background polarisation data in the presence of polarisation angle miscalibration without relying on any assumptions about the Galactic foreground angular power spectra and in particular on their EB correlation. We propose a new analysis framework based on a generalised parametric component separation approach, which accounts simultaneously on the presence of galactic foregrounds, relevant instrumental effects and external priors. We find that upcoming multi-frequency CMB data with appropriate calibration priors will allow producing an instrumental-effect-corrected and foreground-cleaned CMB map, which can be used to estimate the isotropic birefringence angle and the tensor-to-scalar ratio, accounting on statistical and systematic uncertainties incurred during the entire procedure. In particular, in the case of a Simons Observatory-like, three Small Aperture Telescopes, we derive an uncertainty on the birefringence angle of $\sigma(\beta_{b}) = 0.07^\circ$ (0.1$^\circ$), assuming the standard cosmology and calibration priors for all (single) frequency channels with the precision of $\sigma(\alpha_i)= 0.1^\circ$ as aimed at by the near future ground-based experiments. This implies that these experiments could confirm or disprove the recently detected value of $\beta_b=0.35^\circ$ with a significance between $3$ and $5 \sigma$. [abridged version]Comment: 20 pages, 9 figure

Concert recording 2019-10-09

[Track 1]. Trio in E-flat Major, K. 498, Kegelstatt (1786)... I. Andante [Track 2]. II. Menuetto-trio [Track 3]. III. Rondeaux-allegretto / W.A. Mozart -- [Track 4]. Marchenerzahlungen, op. 132 (1853). I. Lebhaft, nicht zu schnell [Track 5]. II. Lehaft und sehr markirt [Track 6]. III. Ruhiges tempo, mit zartem ausdruck [Track 7]. IV. Lebhaft, sehr markirt - Etwas ruhigeres tempo / R. Schumann -- [Track 8]. Selections from Eight pieces, op. 82 (1910). I. Andante [Track 9]. II. Allegro con moto [Track 10]. III. Andante con moto - Andante [Track 11]. IV. Allegro agitato / M. Bruch