| Description |
A central challenge in astrophysics today is to understand the complex processes of galaxy formation: the development of galactic structure, the conversion of gas into stars, and the growth of supermassive black holes. The far-infrared / submillimetre waveband is of particular importance for studying these processes because roughly half of the cosmic energy density produced by galaxies arises from optical/UV starlight that has been absorbed by dust and reradiated at these wavelengths. Existing surveys are already presenting a serious challenge for theorists, revealing many more luminous, massive galaxies at high redshifts than are predicted by simple prescriptions within the hierarchical merging paradigm. Submillimetre surveys however have been extremely limited but have already provided tantalizing clues to a strongly evolving population of infrared-luminous galaxies.We propose HerMES, the Herschel Multi-tiered Extragalactic Survey, to chart the formation and evolution of infrared galaxies throughout cosmic history. HerMES consists of a nested set of fields that will bring unprecedented depth and breadth to the study of infrared galaxies. We will use HerMES to measure the bolometric emission of infrared galaxies, study the evolution of the luminosity function, measure their clustering properties, and probe populations of galaxies below the confusion limit through lensing and statistical techniques. HerMES is closely coordinated with the PACS Evolutionary Probe survey. We will make maximum use of ancillary surveys from radio to X-ray wavelengths to facilitate redshift determination, rapidly identify unusual objects, and understand the relationships between thermal dust emission and other emission mechanisms. HerMES will provide a rich data set legacy for the greater astronomical community to mine for years to come. |
