AAS 205th Meeting, 9-13 January 2005
Session 33 Instrumentation: Ground-Based and Space-Based
Oral, Monday, January 10, 2005, 10:00-11:30am, Royal Palm 1-3

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[33.06] ZEUS: A Submillimeter Grating Spectrometer for Exploring Distant Galaxies

S. Hailey-Dunsheath, T. Nikola, G. J. Stacey, T. Oberst, S. Parshley (Cornell University), D. J. Benford, S. H. Moseley, J. G. Staguhn (NASA Goddard Space Flight Center)

The redshift (Z) and Early Universe Spectrometer (ZEUS) is a long slit echelle grating spectrometer that we are constructing for use in the submillimeter atmospheric transmission windows (350~\mum, 450~\mum, and 610~\mum) on the James Clerk Maxwell Telescope (JCMT). ZEUS has a resolving power of R \equiv \lambda/\Delta\lambda ~1000, optimized for detecting broad, faint lines from extragalactic sources. The detector will be a 4\times64 pixel array of pop-up bolometers (PUD) equipped with superconducting transition edge sensors (TES) linked into a SQUID multiplexed readout. The expected point source sensitivities of the TES PUD at 370~\mum and 444~\mum are 4.3 \times 10-17~W~m-2Hz-1/2 and 2.4 \times 10-17~W~m-2Hz-1/2. For our lab testing we are using a 1\times32 pixel array of thermistor sensed bolometers from GSFC. This array has delivered the requisite sensitivity and spectral coverage for a successful first light at the JCMT in the 350~\mum and 450~\mum windows. We hope to put ZEUS on the JCMT in the spring of 2005.

ZEUS is optimized to quickly obtain spectra of point sources over very broad bands in the submillimeter windows. In the 350~\mum window, ZEUS will provide an instantaneous 53 resolution element spectrum, for each of 4 spatial elements on the sky. The roughly 10% bandwidth 350~\mum window can therefore be covered with just two settings of the grating. Each pixel is mapped into 5'' on the sky (roughly \lambda/D at 350~\mum), so that the field of view is 5''\times20''. At 610~\mum, the slit is opened to 10'' (2 pixels) resulting in a resolving power of around 500. ZEUS can quickly change wavelength or telluric window, adapting well to the demanding weather conditions in the short submillimeter windows.

Our primary scientific objectives are to (1) Investigate Ultraluminous Infrared Galaxies (ULIGs) via their [C~{\small I}] and mid-J CO line emission -- what are the origins of their tremendous infrared (IR) luminosities? Why are some ULIGs weak in the 158~\mum [C~{\small II}] line? (2) Probe star formation in the early Universe using highly redshifted far-IR fine-structure line emission -- especially that of the 158~\mum [C~{\small II}] line. How strong are starbursts in the early Universe? and (3) Provide redshifts for all 850~\mum SCUBA sources, providing source distance, luminosity, and number counts as a function of redshift. What is the evolutionary history of starformation in the early Universe?

This project is supported by NSF grant AST-0096881.

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© 2004. The American Astronomical Society.