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The search for the primordial B-modes of the cosmic microwave background (CMB) relies on the separation from the brighter foreground dust signal. In this context, the characterisation of the spectral energy distribution (SED) of thermal dust in polarization has become a critical subject of study. We present a power-spectra analysis of Planck data, which improves on previous studies by using the newly released SRoll2 maps that correct residual data systematics, and by extending the analysis to regions near the Galactic plane. Our analysis focuses on the lowest multipoles between l=4 and 32, and three sky areas with sky fractions of fsky = 80%, 90%, and 97%. The mean dust SED for polarization and the 353 GHz Q and U maps are used to compute residual maps at 100, 143 and 217 GHz, highlighting spatial variations of the dust polarization SED. Residuals are detected at the three frequencies for the three sky areas. We show that models based on total intensity data are underestimating by a significant factor the complexity of dust polarized CMB foreground. Our analysis emphasizes the need to include variations of polarization angles of the dust polarized CMB foreground. The frequency dependence of the EE and BB power spectra of the residual maps yields further insight. We find that the moments expansion to the first order of the modified black-body (MBB) spectrum provides a good fit to the EE power-spectra. This result suggests that the residuals could follow mainly from variations of dust MBB spectral parameters. However, this conclusion is challenged by cross-spectra showing that the residuals maps at the three frequencies are not fully correlated, and the fact that the BB power-spectra do not match the first order moment expansion of a MBB SED. This work sets new requirements for simulations of the dust polarized foreground and component separation methods (abridged), 13 pages, 13 figures, Accepted for publication in the Cosmology section of A&A journal

Recent climate change is a consequence of the greenhouse effect and human activity, and is directly responsible for extreme events such as heatwaves (see report of the French Academie des Sciences). Human thermoregulation depends more on behavior than on biology Air conditioning and building structure play an essential role. The 2003 heatwave was not a unique event. Preventive measures reduced mortality during subsequent heatwaves. Most deaths were due to heat stroke associated with dehydration. During strenuous exercise, especially during military training, heat stroke requires specific treatment. Temperature/ global mortality and temperature/cardiovascular mortality curves are both U-shaped. Usually, global mortality increases winter and is linked to temperature. During summer, global mortality increases only when heatwaves occur. Climate change participates in the spread of infectious diseases. Nevertheless, in continental France, for the moment, climate change is not a major factor in the incidence of infectious diseases, despite the fact that several bacteria, viruses and vectors are temperature-sensitive. The situation in Reunion, French Polynesia and French Departments of America is more complicated, due to their geographic heterogeneity. Some areas are more exposed to the climatic risk and could act as a gateway for new infections and mutations. The dramatic loss of biodiversity is partly a consequence of climate change. It increases the transmissibility of some pathogens and can also potentially lead to an increase in autoimmune diseases and obesity. Climate change plays a important role in allergic diseases, through changes in the diffusion and composition of pollens. These modifications are being monitored by several observatories. Six different veterinary diseases, including several zoonoses, are of particular concern.

Measurements of Cosmic Microwave Background (CMB) anisotropy have served as the best experimental probe of the early universe to date. The inflationary paradigm, inspired in part by the extreme isotropy of the CMB, is now a cornerstone in modern cosmology. Inflation has passed a series of rigorous experimental tests, but we still do not understand the physical mechanism or energy scale behind inflation. A general prediction of inflation and one that can provide certain insights into inflationary physics is a background of primordial gravitational waves. These perturbations leave a distinct signature in the CMB B-modes of polarization. The EPIC (Experimental Probe of Inflationary Cosmology) study team has investigated several CMB polarization mission concepts to carry out a definitive measurement of the inflationary B-mode polarization spectrum. In this report we study a mission with an aperture intermediate between the two missions discussed in our previous report. EPIC-IM's increased aperture allows access to a broader science case than the small EPIC-Low Cost mission. In addition to the search for inflationary gravitational waves, the increase aperture allows us to mine the scale polarization and lensing shear polarization signals down to cosmological limits, so that we extract virtually all the cosmological information available from the CMB. In addition, a modest number of channels operating at higher frequencies allows for an all-sky measurement of polarized Galactic dust, which will provide a rich dataset for Galactic science related to magnetic fields. Using a combination of a large sensitivity focal plane with a new optical design, and an efficient 4K mechanical cooler, EPIC-IM realizes higher sensitivity than EPIC-Comprehensive Science mission., 157 pages. This report presents the EPIC mission concept for NASA's Inflation Probe (CMBpol) for CMB polarization measurements with an aperture intermediate between the previous EPIC-Low Cost and Comprehensive Science missions studied in arXiv:0805.4207

The Planck cryo-system comprises the following main elements: - The warm radiator of the Payload Module, maintained in the 260-280 K range - The radiating surfaces on the Payload Module (PPLM), which passively cool the payload below ~50 K on the 3rd V-groove, and ~40 K on the reflectors - The 20 K Sorption Cooler, which is pre-cooled by the passive radiators to 60 K and cools the LFI focal plane and the HFI interface to ~18 K - The 4 K cooler, which is pre-cooled by the passive radiators and the 20 K cooler and cools the outer parts of the HFI-FPU and the LFI reference loads to ~4 K - the 0.1 K dilution cooler, which is pre-cooled by the passive radiators, the 20 K cooler, and the 4 K cooler, and cools the inner HFI-FPU box to ~1.6K and the HFI detector plane to ~0.1 K. These elements have been developed by JPL and Industry within the two instruments consortia and under the overall management of the Herschel-Planck Project Team. The Sorption Cooler is common to both instruments but managed by the LFI Project Manager. The two other coolers were developed by the HFI team. The main objective of this document is to define the optimum operation of this complex cryo system during: - cool-down of the system after launch, and in the early stage of the mission; - tuning of the system; - routine operations; - special operations such as the switchover between the two Sorption Coolers, and their regeneration; - anomalies and contingencies. The document also contains information about the expected lifetime of the elements.

The Cosmic Infrared Background (CIB) peaks in the Far-Infrared (FIR), and its Spectral Energy Distribution (SED) is now well constrained. Thanks to recent facilities and Spitzer, the populations contributing to the CIB are being characterized: the dominant galaxy contributions to the FIR CIB are Luminous IR galaxies (LIRGs) at 0.52. These populations of galaxies experience very high rates of evolution with redshift. Because of confusion, the CIB is (and will remain in some domains) partially resolved and its contributing galaxies SEDs are not well constrained. We discuss all these aspects and show how confusion limits Spitzer observations, and how to overcome it in order to study the unresolved part of the CIB., Comment: 13 pages, 6 figures. To appear in "The Spitzer Space Telescope: New Views of the Cosmos", conference proceedings held November 2004 in Pasadena, Eds L. Armus

In recent years it became clear that a population of galaxies radiating most of their power in the far-infrared contribute an important part of the whole star formation activity in the universe. These galaxies emit up to 99% of their energy output in the infrared by dust. The optical properties of dust in galaxies are thus very important to understand this population. Mayo Greenberg who has brought many of the ideas underlying our understanding of the physics of interstellar dust has been a pioneer in predicting the important role of organic solid material formed on dust grains in molecular clouds and of potential importance of transient heating of very small particles. It appeared with the ISO data on galaxies and even more today with the first Spitzer data that these mechanisms are important globally for the observations of infrared galaxies at significant redshifts. The understanding of their evolution is one of the keys to the understanding of galaxy built up and evolution., Comment: 13 pages, 5 figures. To appear in the proceedings of the conference "Penetrating Bars through Masks of Cosmic Dust: The Hubble Tuning Fork strikes a New Note" held June 7-12th, 2004 in Pilanesberg National Park, South Africa

We present the results of a mid-infrared (7 micron) imaging survey of a sample of 24 starless dense cores carried out at an angular resolution of 6 arcsec with the ISOCAM camera aboard the Infrared Space Observatory (ISO). The targeted cores are believed to be pre-stellar in nature and to represent the initial conditions of low-mass, isolated star formation. In previous submillimeter dust continuum studies of such pre-stellar cores, it was found that the derived column density profiles did not follow a single power-law such as N[H2] \propto r^(-1) throughout their full extent but flattened out near their center. These submillimeter observations however could not constrain the density profiles at radii greater than ~ 10000 AU. The present absorption study uses ISOCAM's sensitivity to map these pre-stellar cores in absorption against the diffuse mid-infrared background. The goal was to determine their structure at radii that extend beyond the limits of sensitivity of the submillimeter continuum maps and at twiceas good an angular resolution. Among the 24 cores observed in our survey, a majority of them show deep absorption features. The starless cores studied here all show a column density profile that flattens in the center, which confirms the submillimeter emission results. Moreover, beyond a radius of ~ 5000-10000 AU, the typical column density profile steepens with distance from core center and gets steeper than N[H2] \propto r^(-1), until it eventually merges with the low-density ambient molecular cloud. At least three of the cores present sharp edges at R ~ 15000-30000 AU and appear to be decoupled from their parent clouds, providing finite reservoirs of mass for subsequent star formation., 28 pages, LaTeX, 10 figures, Accepted for publication in Astronomy & Astrophysics. Higher quality figures available at http://www.astro.uni-jena.de/Users/bacmann/papers

FIRBACK is a one of the deepest surveys performed at 170 microns with ISOPHOT onboard ISO, and is aimed at the study of cosmic far infrared background sources. About 300 galaxies are detected in an area of four square degrees, and source counts present a strong slope of 2.2 on an integral "logN-logS" plot, which cannot be due to cosmological evolution if no K-correction is present. The resolved sources account for less than 10% of the Cosmic Infrared Background at 170 microns. In order to understand the nature of the sources contributing to the CIB, and to explain deep source counts at other wavelengths, we have developed a phenomenological model, which constrains in a simple way the luminosity function evolution with redshift, and fits all the existing deep source counts from the mid-infrared to the submillimetre range. Images, materials and papers available on the FIRBACK web: http://wwwfirback.ias.u-psud.fr wwwfirback.ias.u-psud.fr, Comment: proceedings of "ISO Surveys of a Dusty Universe", eds. D. Lemke, M. Stickel, K. Wilke, Ringberg, 8-12 Nov 1999, to appear in Springer 'Lecture Notes of Physics'. 8 pages, 7 eps figures, .sty included

This thesis presents a work on the cosmic diffuse background fluctuations in the infrared and micro-wave wavelengths. (1) A cirrus color study shows the increase of the color B(60 microns)/B(100 microns) from 0.21 to 0.28 when cirrus brightness is lower then 3 MJy/sr. This is due to an increase of the very small grains abundance at high latitude, where supernovae winds cause erosion and fragmentation of grains. (2) Separation between cirrus and cosmic infrared background (CIB) fluctuations with colors B(60)/B(100), B(60)/B(170), B(100)/B(170) is not efficient because of the closeness of the two spectra. This analyse should be done at longer wavelengths with the futur missions Planck and Herschel. (3) Power spectrum of the CIB fluctuations shows no correlation. We deduce an upper limit of 0.6 on the infrared bias. This reveal that galaxies forming the CIB fluctuations are at low redshift. We must explore bigger maps to detect correlation. (4) A statistical way to separate cosmic micro-wave backgound (CMB) fluctuations from kinetic Sunyaev-Zel'dovich (SZ) effect could be a law known in advance between the kinetic SZ effect and the covariance product between the thermal SZ effect and the mixture map (CMB + kinetic SZ)., Cette thèse présente un travail sur le fond diffus extragalactique dans les domaines de longueurs d'onde infrarouge et millimétrique. (1) L'étude de la couleur (ou rapport de brillance) des cirrus aux longueurs d'onde 60 et 100 microns a montré une augmentation de celle-ci de B(60)/B(100)=0.21 à 0.28 pour des brillances inférieures à B(100)=3 MJy/sr. Ceci se traduit par une augmentation des très petits grains de poussières dans les régions diffuses de haute latitude provoquée par l'érosion et la fragmentation des grains par les ondes de choc des supernovae. (2) La séparation entre les cirrus et les fluctuations du fond diffus infrarouge extragalactique à l'aide des couleurs B(60)/B(100), B(60)/B(170), B(100)/B(170) s'est révélée non efficace, car les spectres des deux composantes sont trop proches à ces longueurs d'onde. Il faudra renouveler l'étude aux plus grandes longueurs d'onde de Planck et Herschel. (3) Le spectre de puissance des fluctuations du fond diffus infrarouge extragalactique ne montre aucune corrélation particulière. On en déduit un biais des galaxies infrarouges inférieur à 0.6. Ceci implique que les galaxies formant les fluctuations du fond sont à bas redshift. On espère détecter des corrélations en sondant les cartes plus grandes de SPITZER. (4) la séparation statistique du fond diffus cosmologique (FDC) et de l'effet Sunyaev-Zel'dovich (SZ) cinétique pourrait se faire à l'aide d'une loi à priori entre l'effet SZ cinétique et le produit de covariance entre la carte de mélange (FDC+SZ cinétique) et l'effet SZ thermique.

In this dissertation, I present a theoretical work addressing two fundamental questions of modern cosmology. First, galaxy formation models suffer from problems of which the over-cooling is presumably the most serious. In order to propose a solution to it, I explore the physics of the biphasic magnetised Interstellar Medium (ISM) of our Galaxy. I show how interferences of Alfvén waves within a cloud of the ISM strongly enhance the internal magneto-turbulent energy density. I then study numerically the energy transport and injection mechanisms in a system of magnetised clouds. On the one side, the motions of clouds connected by a magnetic field spread energy over the whole system. On the other side, they inject energy into the clouds by generating internal hydromagnetic waves. The latter provide a non-thermal pressure which opposes external compression and lengthens the life time of the system. I finally show that the time of energy dissipation is several orders of magnitude longer than the one of the corresponding homogeneous system. The energy is effectively stored on several dynamical time scales. Considering a toy model of a biphasic protogalaxy, I show that the cloud systems in the ISM and the protogalaxy are dynamically equivalent. To solve the over-cooling, I suggest to transpose the results obtained for the ISM to the protogalaxy case. Second, the origin of magnetic fields in cosmology eluded any attempt of explanation. Yet its role in structuring the ISM and its involvement in galaxy formation are evident. Here I propose a new magnetogenesis mechanism operating on large scales at the reionisation of the Universe. On galaxy scales, the magnetic field produced is roughly eight orders of magnitude stronger than in usual models. Furthermore, it is generated preferably on large scales, small scale fields being largely suppressed. These two properties allow the model to account for fields detected in large scale structures.; Ma thèse est le fruit d'un travail théorique centré sur deux questions fondamentales de la cosmologie actuelle: la formation des galaxies d'une part, et l'origine des champs magnétiques à grande échelle d'autre part. Je propose une solution au problème du sur-refroidissement dont souffrent les modèles de formation des galaxies. Pour cela, à l'aide d'un modèle analytique simple, puis au moyen de simulations numériques, j'explore les mécanismes de transfert et de stockage d'énergie par ondes d'Alfvén en œuvre dans le milieu interstellaire (MIS) biphasique. Je montre d'une part que les interférences des ondes internes aux nuages du MIS, négligées dans les études précédentes, renforcent l'efficacité d'injection d'énergie. D'autre part, les mouvements des nuages redistribuent l'énergie à l'échelle du système entier. Ils injectent aussi de l'énergie dans les nuages. Les modes vibratoires internes excités s'opposent à la compression des nuages et prolongent la durée de vie du système. Les nuages magnétisés constituent alors un réservoir d'énergie sur plusieurs temps dynamiques. A l'aide d'un modèle de protogalaxie biphasique, je montre que la dynamique des nuages du MIS et celle d'une protogalaxie sont équivalentes. Pour résoudre le sur-refroidissement, je propose la transposition des résultats du MIS au cas protogalactique. Malgré les diverses tentatives passées, l'origine du champ magnétique en cosmologie n'a pas trouvé d'explication satisfaisante. Or, sa place au sein du MIS et son rôle dans la formation des galaxies sont manifestes. Je propose dans ma thèse un nouveau mécanisme de magnétogenèse efficace à grande échelle, opérant à la réionisation de l'Univers, et reposant sur la pression de radiation anisotrope et inhomogène fournie par les premières structures lumineuses. A l'échelle galactique, le champ magnétique que j'obtiens est huit ordres de grandeur plus intense que dans les modèles habituels. De plus, il est généré avant tout aux grandes échelles, les champs à petite échelle étant largement supprimés. Ces deux propriétés permettent au modèle proposé de rendre compte des champs observés dans les grandes structures.

The ESA mission Planck provides us with an unprecedented opportunity to measure, in an extremely precise way, the polarisation of the millimeter and sub-millimeter, galactic and extragalactic emission; it should enable us in particular to measure the polarisation of the Cosmic Microwave Background (CMB). In the first chapter of this thesis, we briefly explain the scientific motivations of such a measurement, and describe the instrumental technology which will make it possible. In the second chapter, we model the statistical behaviour of the polarised galactic emission (in particular the one generated by the dust, which is specially important for the High Frequency Instrument -HFI- aboard Planck). In the third chapter, we describe a multi-frequency filtering method, allowing one to separate the different astrophysical components contributing to the microwave polarised emission, and giving also an estimate of the errors in the measurement of their statistical properties (power spectra). We estimate these errors for the CMB in particular. In the fourth chapter, we compute the errors on the measurement of the different cosmological parameters as a consequences of the errors estimated in the last chapter. In a fifth chapter, we compute the contribution to the anisotropies of the CMB of moving gravitationel lenses, caused by a population of galaxy clusters and groups. Finally, in a sixth chapter, we present a simple semi-analytical model of galaxy formation, where the Star Formation Rate is controlled by the temperature of the (hot) inter-galactic medium.; La mission ESA Planck offre une opportunité sans précédent de mesurer de manière très précise la polarisation de l'émission Galactique et extragalactique dans le domaine millimétrique et sub-milli\-métrique ; elle devrait notamment permettre de mesurer la polarisation du Fond Cosmique Micro-ondes (FCM). Dans le premier chapitre, nous expliquons brièvement l'intérêt scientifique d'une telle mesure, et revoyons les technologies instrumentales qui la permettent. Dans le second chapitre, nous modélisons les caractéristiques statistiques de l'émission galactique polarisée, en particulier celle des poussières (plus particulièrement importante pour l'instrument haute fréquence -HFI- de Planck). Dans le troisième chapitre, nous présentons une méthode de filtrage multi-fréquence permettant la séparation des différentes composantes astrophysiques de l'émission millimétrique et sub-millimétrique, et permettant de quantifier les erreurs de la mesure des propriétés statistiques (spectre de puissance) de ces différents processus, en particulier le FCM. Dans le quatrième chapitre, nous estimons l'erreur commise sur la mesure des paramètres cosmologiques, conséquence des erreurs estimées au chapitre précédent. Dans un cinquième chapitre, nous estimons la contribution aux anisotropies du FCM de l'effet de lentille gravitationnelle en mouvement, causé par une population d'amas et de groupes de galaxies. Enfin, dans un sixième chapitre, nous présentons un modèle semi-analytique simple de formation de galaxies, où le taux de formation d'étoiles est controlé par la température du milieu intergalactique.