A 12 μm ISOCAM survey of the ESO-Sculptor field

We present a detailed reduction of a mid-infrared 12 μm (LW10 filter) ISOCAM open time observation performed on the ESOSculptor Survey field (Arnouts et al. 1997, A&AS, 124, 163). A complete catalogue of 142 sources (120 galaxies and 22 stars), detected with high significance (equivalent to 5σ), is presented above an integrated flux density of 0.24 mJy. Star/galaxy separation is performed by a detailed study of colour-colour diagrams. The catalogue is complete to 1 mJy and, below this flux density, the incompleteness is corrected using two independent methods. The first method uses stars and the second uses optical counterparts of the ISOCAM galaxies; these methods yield consistent results. We also apply an empirical flux density calibration using stars in the field. For each star, the 12 μm flux density is derived by fitting optical colours from a multi-band χ^2 to stellar templates (BaSel-2.0) and using empirical optical-IR colour-colour relations. This article is a companion analysis to our 2007 paper (Rocca-Volmerange et al. 2007, A&A, 475, 801) where the 12 μm faint galaxy counts are presented and analysed per galaxy type with the evolutionary code PÉGASE.3

The large-scale environments of radio-loud active galactic nuclei and their evolution across cosmic time

Emerging from the cosmic web, galaxy clusters are the most massive gravitationally bound structures in the universe. Thought to have begun their assembly at 2 1.5 where major assembly is in progress. The search for galaxy clusters at high redshift, so far, has been mildly successful and only a handful of clusters at z > 1.5 have been confirmed. Because this redshift range was essentially unreachable with previous instrumentation, it was dubbed a ‘redshift desert’. The work presented in this thesis has made a major contribution to this field. The Clusters Around Radio- Loud AGN (CARLA) survey, a 400 hr targeted Warm Spitzer program, observed 420 radio-loud AGN (active galactic nuclei) at 1.3 1.5. We also showed that radio-loud AGN reside in denser environments than similarly massive galaxies. This makes high-redshift clusters around radio-loud AGN particularly interesting as they can reveal how galaxies in the most massive dark matter halos assembled. A complementary project, HERGE (Herschel Radio Galaxy Evolution Project) observed a sample of 71 radio galaxies at 1 < z < 5 at far-IR wavelengths with the Herschel Space Observatory. Supporting data in the mid-IR, partially in the near-IR and at sub-mm wave- lengths allow to study cluster fields in more detail. A pilot project on a single field showed that we can identify cluster members and constrain their star-formation properties. These projects laid the foundation for future work, which will make a significant impact on understanding the formation of the most massive structures over several billion years

Influence de la couverture de neige de l'hémisphère nord sur la variabilité interannuelle du climat

La neige peut couvrir jusqu'à 40% des terres immergées de l'hémisphère Nord en hiver. De par son influence sur le bilan d'énergie en surface, elle constitue donc une source potentielle de variabilité et de prévisibilité climatique aux échelles mensuelles à saisonnières. Au-delà de ses effets locaux, la couverture neigeuse peut, à l'instar des surfaces océaniques, engendrer des téléconnexions et ainsi moduler le climat de régions plus lointaines. Cette thèse revisite plusieurs aspects des liens neige-climat en utilisant à la fois les jeux de données observées, les simulations réalisées pour le 4ème rapport du Groupe Intergouvernemental d'experts sur l'Evolution du Climat (GIEC), ainsi que le modèle atmosphérique ARPEGE-Climat pour réaliser des tests de sensibilité. L'influence de la neige eurasiatique/himalayenne sur la mousson indienne d'été, largement évoquée dans la littérature, est remise en cause par l'analyse des données observées étendues à la période 1967-2006. Toutefois, un prédicteur lié à la circulation atmosphérique de grande échelle sur le Pacifique Nord est proposé pour améliorer les prévisions saisonnières statistiques de la mousson indienne. L'influence des étendues de neige sibériennes en automne sur la variabilité atmosphérique hivernale de l'hémisphère Nord semble quant à elle plus robuste dans les observations. Si les modèles couplés du GIEC sont incapables de reproduire cette téléconnexion, les expériences de sensibilité réalisées avec ARPEGE-Climat confirment le mécanisme physique proposé dans la littérature, à condition que la perturbation en surface soit importante et que l'état moyen de la circulation extratropicale simulé soit suffisamment réaliste. Finalement, la prévisibilité de l'atmosphère associée à l'enneigement est quantifiée de façon plus systématique avec ARPEGE-Climat. Si les résultats montrent un impact mitigé sur la circulation de grande échelle, la relaxation/initialisation du modèle vers/avec des masses de neige plus réalistes permet une meilleure prévisibilité des températures de surface sur l'Europe et l'Amérique du Nord. La neige représente donc une source de prévisibilité climatique non négligeable à l'échelle locale et peut influencer à distance la circulation atmosphérique extratropicale. Les téléconnexions neige-climat doivent être cependant être confirmées dans les années qui viennent, et constituent encore un exercice difficile pour l'état de l'art des modèles de climat.Snow can cover more than 40% of the Earth's land surface during the Northern Hemisphere winter. Because of its influence on the energy balance at the surface, it represents therefore a potential source of climate variability and predictability at the seasonal and monthly timescales. Beyond its local effects, snow cover is able to generate some teleconnections and thereby modulate some remote climatic phenomena. This thesis revisits several aspects of snow-climate relationships using both observed data sets, simulations from the 4th report of the Intergovernmental Panel on Climate Change (IPCC) and the ARPEGE-Climat atmospheric model to perform sensitivity experiments. The influence of Eurasian/Himalayan snow on the Indian summer monsoon, widely reported in the literature, is questioned by the analysis of observed data extended to the 1967-2006 period. However, a predictor associated with large-scale atmospheric circulation over the North Pacific region is proposed to improve the statistical seasonal forecasts of the monsoon rainfall. The influence of the Siberian snow extent in fall on the variability of the wintertime Northern Hemisphere atmosphere seems more robust in the observations. If the IPCC coupled models are unable to reproduce this teleconnection, the sensitivity experiments performed with ARPEGE-Climat confirm the physical mechanism proposed in the literature, depending on the amplitude of the forcing and on the realism of the simulated extratropical circulation mean state. Finally, the atmospheric predictability related to snow is quantified more systematically with ARPEGE-Climat. If the results show a mixed impact on the large scale circulation, relaxation/initialization of the model towards/with a more realistic snow mass leads to a better predictability of surface temperature over Europe and North America. Consequently, snow represents a significant source of climate predictability at the local scale and have remote influence on the extratropical atmospheric circulation. Snow-climate teleconnections should however be confirmed in the coming years and are currently poorly captured by the state-of-the-art climate models

Proceedings of the 8th International Conference on Energy Efficiency in Domestic Appliances and Lighting

At the EEDAL'15 conference 128 papers dealing with energy consumption and energy efficiency improvements for the residential sector have been presented. Papers focused policies and programmes, technologies and consumer behaviour. Special focus was on standards and labels, demand response and smart meters. All the paper s have been peer reviewed by experts in the sector.JRC.F.7-Renewables and Energy Efficienc