Observing Cold Dust with Herschel/SPIRE

Abstract

A major component of the emission of many galaxies is in the Far Infrared and the Sub-mmillimeter. UV photons from stars are absorbed by dust and re-emitted at longer wavelengths. Fairly cold dust was found in large spirals by the Infrared Space Observatory and the Spitzer Observatory, but their longest wavelength filters were centered at 200 and 160 microns respectively, restricting detection to dust warmer than about 15 Kelvin, and missing a major part of the dust mass. The Spectral and Photometric Imaging Receiver SPIRE ([1]) is one of the 3 instruments on board of the Herschel Space Observatory that was launched on 14 May 2009. The instrument hosts bolometer arrays with broadband photometric filters, centered at 250, 350 and 500 µm, as well as an imaging Fourier Transform Spectrometer, covering the range from 200 to 670 µm at 3 different spectral resolutions. This long wavelength coverage will, among many other subjects, allow for studies that take the entire dust content of a galaxy into account. The 3 instruments of Herschel are currently undergoing performance-and science-verification operations, followed by the execution of the first large key science programs. A call for smaller open time programs is expected to be issued after the science verification phase is complete.