Fitting the integrated Spectral Energy Distributions of Galaxies

Fitting the spectral energy distributions (SEDs) of galaxies is an almost universally used technique that has matured significantly in the last decade. Model predictions and fitting procedures have improved significantly over this time, attempting to keep up with the vastly increased volume and quality of available data. We review here the field of SED fitting, describing the modelling of ultraviolet to infrared galaxy SEDs, the creation of multiwavelength data sets, and the methods used to fit model SEDs to observed galaxy data sets. We touch upon the achievements and challenges in the major ingredients of SED fitting, with a special emphasis on describing the interplay between the quality of the available data, the quality of the available models, and the best fitting technique to use in order to obtain a realistic measurement as well as realistic uncertainties. We conclude that SED fitting can be used effectively to derive a range of physical properties of galaxies, such as redshift, stellar masses, star formation rates, dust masses, and metallicities, with care taken not to over-interpret the available data. Yet there still exist many issues such as estimating the age of the oldest stars in a galaxy, finer details ofdust properties and dust-star geometry, and the influences of poorly understood, luminous stellar types and phases. The challenge for the coming years will be to improve both the models and the observational data sets to resolve these uncertainties. The present review will be made available on an interactive, moderated web page (sedfitting.org), where the community can access and change the text. The intention is to expand the text and keep it up to date over the coming years.Comment: 54 pages, 26 figures, Accepted for publication in Astrophysics & Space Scienc

Observations of the High Redshift Universe

(Abridged) In these lectures aimed for non-specialists, I review progress in understanding how galaxies form and evolve. Both the star formation history and assembly of stellar mass can be empirically traced from redshifts z~6 to the present, but how the various distant populations inter-relate and how stellar assembly is regulated by feedback and environmental processes remains unclear. I also discuss how these studies are being extended to locate and characterize the earlier sources beyond z~6. Did early star-forming galaxies contribute significantly to the reionization process and over what period did this occur? Neither theory nor observations are well-developed in this frontier topic but the first results presented here provide important guidance on how we will use more powerful future facilities.Comment: To appear in `First Light in Universe', Saas-Fee Advanced Course 36, Swiss Soc. Astrophys. Astron. in press. 115 pages, 64 figures (see http://www.astro.caltech.edu/~rse/saas-fee.pdf for hi-res figs.) For lecture ppt files see http://obswww.unige.ch/saas-fee/preannouncement/course_pres/overview_f.htm

Bean research and production needs in Malawi

The two days of discussion highlighted several areas of need in developing a Bean Production Improvement Programme. The most critical need appeared to be an evaluation of seed availability and the use of new seed varieties within existing mixtures. Other ideas included intensifying the maize-bean intercropping and mid-season plantings. Also considered was the growing of beans on the flu- cured tobacco estates and relayed into sugarcane ratoons. There was concern about possible duplication of effort with the Maize Commodity Team's work on spatial arrangements of maize bean intercrops. (AS)Durante los 2 dias de discusiones se destacaron algunas areas en que se necesitan desarrollar en un programa de mejoramiento de produccion de frijol. La necesidad mas critica parece ser una evaluacion de la disponibilidad de semilla y el uso de nuevas var. dentro de las mezclas existentes. Otras ideas incluyen la intensificacion del cultivo asociado maiz-frijol y las siembras a mediados de la estacion de cultivo. Igualmente se considero el cultivo del frijol en las fincas donde se siembra tabaco para ser curado con aire caliente, y en relevo entre las socas de cana. Hubo interes sobre la posible duplicacion de esfuerzo con el trabajo del Maize Commodity Team en arreglos espaciales de maiz-frijol en asociacion. (RA-CIAT

Natural vegetation strips (NVS) and Gmelina cropping systems

Recent rising demand for timber in Northern Mindanao, Philippines has driven smallholder farmers to plant fast-growing timber species, mostly Gmelina arborea, within their farms. The trees are commonly planted in portions of farms as block planting, along farm boundaries, or established along contour strips. Both natural vegetation strips (NVS) and tree cropping systems are examined here from biophysical and economic perspectives. In this paper, farmer surveys are reported with the aim of determining how livestock are raised in relation to the agricutural and tree components in both NVS and Gmelina block planting systems. The contribution of the animals to the productivity of each cropping system is established. Following the survey, the computer model, Soil Changes Under Agroforestry, is used to predict crop and tree yields for a number of years. These yields, in combination with the economic data collected, are input to a benefit-cost analysis that determines the long-term economic productivity of the cropping systems, with and without the animal component. The integration of livestock within both cropping systems was found to enhance economic productivity. The Gmelina system was the more profitable of the two systems but required a greater investment