ZEUS: the redshift (z) and early universe spectrometer

The redshift (z) and early Universe spectrometer (ZEUS) is an echelle grating spectrometer optimized to study star formation in the universe from about 1--2 billion years after the Big Bang to the present epoch by observing spectral lines in the submillimeter bands. ZEUS has a resolving power R ˜ 1000 optimized for extragalactic point source sensitivity. At present, ZEUS employs a 1 × 32 pixel thermister-sensed bolometer array configured to deliver simultaneous 16-element spectra in the 350 and 450 μm windows for a point source. When completed, ZEUS will have a 12 × 64 pixel TES-sensed bolometer array, delivering an instantaneous 64-element (6.4% bandwidth) spectrum at 12 spatial positions on the sky. ZEUS can be used on most large-aperture submillimeter telescopes, including the JCMT, CSO, SMT, and APEX. We obtained our first light on the CSO in early April 2006. Our primary science goals are to (1) trace star formation in the early universe by observing redshifted far-IR fine structure lines from distant (z ˜ 0.7 - 6) galaxies, (2) measure the redshifts of optically obscured submillimeter galaxies by detecting their bright 158 μm [C II] line emission, and (3) study star formation in starbursts and ULIRGs by observing their [C I] and mid-J CO rotational line emission.