BLAST: studying cosmic and Galactic star formation from a stratospheric balloon

Understanding the history of the formation of stars and evolution of galaxies is one of the foremost goals of astrophysics. While stars emit most of their energy at visible and ultraviolet wavelengths, during the early stages of star formation these photons are absorbed by the dusty molecular clouds that host and fuel the emerging stars, and re-emitted as thermal radiation at infrared and submillimeter wavelengths. The Balloon-borne Large Aperture Submillimeter Telescope (BLAST) was designed to study the history of obscured star forma- tion in galaxies at cosmological distances and witness the details of the star-formation processes in our own Galaxy, by conducting large- area surveys of the sky at 250, 350, and 500 �m from a long-duration stratospheric balloon platform. Its polarimetric adaptation, BLAST- Pol, will allow us to further probe the strength and morphology of magnetic fields in dust-enshrouded star-forming molecular clouds in our Galaxy. The study of these two diverse, yet highly complemen- tary, topics is the primary scientific motivation for this thesis, which is in two parts. Part One is concerned with the analysis of a combination of the extragalactic dataset collected by BLAST in the 2006 Antarctic cam- paign, which comprises maps containing hundreds of distant, highly dust-obscured, and actively star-forming galaxies, with a wealth of ancillary multi-wavelength data spanning the radio to the ultravio- let. The star-formation rates we observe in massive galaxies at high redshift support downsizing and size evolution. Part Two describes the BLAST-Pol instrument. In particular, we focus on the gondola's primary pointing sensors, the star cameras, and on the design, manufacture and characterization of a polarization IX modulation scheme, comprising a cryogenic achromatic half-wave plate and photolithographed polarizing grids, which has been effectively retrofitted on BLAST-Pol. We report on the construction and deployment of BLAST-Pol, which completed its first successful 9.5-day ight over Antarctica in January 2011 and mapped ten science targets with unprecedented combined mapping speed, sensitivity, and resolution