SCOWL - taking OWL into the submillimetre

SCOWL(1) is a concept for a wide-field sub-mm camera for the OWL telescope. The instrument will be up to an order of magnitude more sensitive per pixel and many orders of magnitude faster at widefield mapping than other facilities available in the next decade. It will significantly broaden the scientific capabilities of OWL. For example, it will be possible to detect cool dust in debris discs like our own Solar System out to 20pc, or detect normal Galaxies like our Milky Way throughout most of the Universe. It will provide a pathfinder for detailed followup with ALMA. In the following, we summarise the science case together with an outline conceptual design, and the predicted capabilities. We show the performance of SCOWL on different sites and with different telescope apertures; major science gains will be realized on a 50m+ telescope on a suitably dry site. 1. SUBMILLIMETRE SCIENCE Emission at submillimetre wavelengths is most sensitive to cool dust and gas, with for example the blackbody radiation from a 10K source (or a 40K source at a redshift of 3) peaking at ~300µm. As a consequence, the main area of submillimetre astronomy is the study of formation processes, be it of planets, stars or galaxies. Sites of formation of these most fundamental structures are generally cool, rich in dust, and hidden by many magnitudes of visual extinction; consequently most of their energy is emitted in the 30- 3000µm region. An additional important feature of the submillimetre continuum emission from dust is that in nearly all situations the emission is optically thin; this ensures that observations probe right to the heart of the most crucial processes and trace emission over a very wide dynamic range of density and mass. In the following sections we outline some of the key science questions that would be addressed by an instrument with the capabilities of SCOWL.