The Submillimeter Astrophysics Group at Cornell University presents:

ZEUS: The High-Redshift (Z) Early Universe Spectrometer

The high-redshift (Z) and Early Universe Spectrometer (ZEUS) is a submillimeter echelle grating spectrometer designed to study the star formation in the Universe from about 2 billion years after the Big Bang to the present by observing the submillimeter and far-infrared spectral lines from distant dusty galaxies.

ZEUS is designed for use in the 350, 450, and 610 micron telluric windows on large submillimeter telescopes. It is designed for a 4x64 pixel array of TES bolometers, held at about 250 mK with a dual stage ³He refrigerator. By changing a bandpass filter it transmits in 5th, 4th, or 3rd order of the echelle, accessing the 350, 450, or 610 micron telluric windows respectively. ZEUS has a resolving power of R~500 to 1500 in these bands, and R~1200 at 370 micron, sufficient to well resolve the CO(7-6) and 370 micron [CI] lines that are spaced by only 1000 km/s. ZEUS instantaneously delivers a 64 element spectrum at any wavelength between 333 - 379 micron (5th order); 422 - 474 micron (4th order) and 590 - 626 micron (3rd order). The high throughput and background limited performance of ZEUS ensures that it is the most sensitive spectrometer available for detection of broad lines from point sources (i.e. galaxies). The pixel size is 5"x5", close to optimal for point source extraction at 350 micron.

At present, we are using a 1x32 pixel array of thermistor sensed bolometers provided by S.H. Moseley's group at Goddard Space Flight Center, that yields an instantaneous spectrum of 32 spectral elements on a single beam on the sky. The larger format array (also provided by GSFC) will yield a 64 element spectrum typically covering a total bandwidth of 6.4% at 4 positions on the sky. Our current array is adequate for work at 350 and 450 micron, however we will require the larger format 4x32 pixel TES-sensed array for good performance at the longer wavelengths (610 micron).

Commissioning Run of ZEUS at the JCMT:

In March/April 2005 ZEUS had its commissioning run at the JCMT. For this first observing run we used our 1x32 pixel thermistor sensed array and we had only the 350 micron band pass filter installed in ZEUS.

Due to weather constrains we did not get science data during the commissioning run.

ZEUS at the CSO: First Light on the Sky

We installed ZEUS at the Caltech Submillimeter Observatory (CSO) for two observing runs in March/April 2006 and May 2006. For these observing runs we installed the 350 and 450 micron band pass filter adjacent to each other, close to the focal plane at the entrance of the detector block. This essentially splits the 1x32 pixel array into a 1x16 pixel array for the 350 micron window in 5th order and a 1x16 pixel array for the 450 micron window in 4th order. This modification allowed us to observe the CO (6-5) and the ¹³CO(8-7) line simultaneously. Despite poor atmospheric transmission (in the order of 1% a long the line of sight) ZEUS got first light observing the region W49. The measured sensitivity of ZEUS was excellent with equivalent single side band values of T_rec(SSB) ~ 100 and 200 K at 450 and 340 micron, respectively.

ZEUS at the CSO: Great Observing Run in December 2006

In this observing run we have setup ZEUS the same as in our first CSO observing run: we have split the 1x32 pixel array into a 1x16 pixel array for the 350 micron window in 5th order and a 1x16 pixel array for the 450 micron window in 4th order. And finally, after many years of observing on Mauna Kea the weather cooperated and we got great data. Among the exciting results is the detection of redshifted (z=1.16) [CII] in a submillimeter galaxy. We also detected the ¹³CO(6-5) line in NGC 253. This is the first detection of a mid-J ¹³CO line from an external galaxy. For more detail please see the observing report.

Acknowledgements:

This work was supported by NSF grants AST-0096881, and AST-0353855, and NASA grants NGT5-50450 and NNG05GK70H.

Selected Publications:

G.J. Stacey, S. Hailey-Dunsheath, T. Nikola, T.E. Oberst, S.C. Parshley, D.J. Benford, J.G. Staguhn, S.H. Moseley, C. Tucker, "ZEUS: The Redshift(z) and Early Universe Spectrometer", in: From Z-Machines to ALMA: (Sub)millimeter Spectroscopy of Galaxies ASP Conference Series, Vol. TBD, 2006, eds. A.J. Baker, J. Glenn, A.I. Harris, J.G. Mangum, and M.S. Yun
ZEUS [CII] Poster
ZEUS First Light Poster
ZEUS Instrument Poster
Stacey, G.J., Hailey-Dunsheath, S., Nikola, T., Parshley, S.C., Benford, D., Moseley, S.H., Staguhn, J.G., and Shafer, R.A. "ZEUS: The Redshift (Z) and Early Universe Spectrometer", 2004, SPIE (Full Paper)
Nikola, T., Hailey-Dunsheath, S., Stacey, G.J., Benford, D.J., Moseley, S.H., Jr., Staguhn, J.G., "ZEUS: A Submillimeter Grating Spectrometer for Exploring Distant Galaxies", 2003, SPIE, 4855, 88, (Full Paper)

Last updated by Thomas Nikola, March 2007