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Paper: The Zpectrometer: an Ultra-Wideband Spectrometer for the Green Bank Telescope
Volume: 375, From Z-Machines to ALMA: (Sub)Millimeter Spectroscopy of Galaxies
Page: 82
Authors: Harris, A.I.; Baker, A.J.; Jewell, P.R.; Rauch, K.P.; Zonak, S.G.; O'Neil, K.; Shelton, A.L.; Norrod, R.D.; Ray, J.; Watts, G.
Abstract: We describe the Zpectrometer, an ultra-wideband radio spectrometer for the Green Bank Telescope (GBT). Observations with this instrument will be important for understanding the star formation, metal production, and structure formation histories of the universe. The Zpectrometer covers the full 13.5GHz-wide Ka band with a set of analog lag correlation spectrometers in a multi-channel correlation radiometer architecture. Its bandwidth and stability, combined with the GBT's collecting area, enable sensitive and efficient spectral searches for molecules in high-redshift galaxies. The instrument is optimized for observations of low-excitation spectral lines from the carbon monoxide (CO) molecule at redshifts of 1.88 ≤ z ≤ 3.43 and 4.76 ≤ z ≤ 7.87. All high-redshift radio molecular detections to date have started from optical redshifts. The Zpectrometer�s wide bandwidth bypasses this selection effect and enables it to detect new classes of sources. In addition to finding precise redshifts, its approximately 150 km s−1 resolution spectra probe kinematic signs of interaction and enable dynamical mass estimates. Because both cold and warm gas emit low-J lines, these observations place critical constraints on radiative transfer models of physical conditions.
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