| Description |
We propose to use SPIRE and PACS in parallel mode to carry out a 720 sq.deg. unbiased imaging survey of the entire Galactic Plane of the Milky Way, uniformly sampling a 2-wide strip centered on the warped midplane in the 70, 170, 250, 350 and 500um photometric bands. The Herschel infrared Galactic Plane Survey (Hi-GAL) embodies the optimum combination of Herschel wavelength coverage, sensitivity, mapping strategy and speed to deliver, in a single and homogeneous dataset of the highest statistical significance, the ultimate census and characterisation (temperature, luminosity, mass and Spectral Energy Distribution) of star forming regions and cold ISM structures in all the environments of the Galactic ecosystem, at unprecedented resolutions, and at all scales from massive objects in protoclusters to the full spiral arm. This will enable decisive steps toward the formulation of a global predictive model of the ISM/star formation cyclic transformation process which is the engine responsible for most of the energy budget in normal star-forming galaxies. It will be a cornerstone to unveil the evolution of galaxies through redshift back to their formation. Hi-GAL will also deliver a dataset of extraordinary legacy value for decades to come, with a strong potential of systematic and serendipitous science in a wide range of astronomical fields, and enabling the optimum use of future major facilities such as ALMA. In addition to a suite of enhanced products, including mosaiced images and source catalogues in all bands, we will create an immediate legacy value by waiving the totality of our proprietary time.The complete 60-600um view of the Milky Way at 10-35 resolution will be unique to Herschel, as it is beyond the capabilities of all of the future planned ground-based and space-borne facilities either for highest resolution (ALMA, SPIRIT, FIRI and SPECS interferometers) or for highest sensitivity (SPICA and SAFIR actively cooled single-dishes). |
