A broadband millimeter-wave spectrometer— Z-spec:Sensitivity and ULIRGs

摘要

Z-Sped ~([1,2,3,4,5,6])is a cryogenic, broadband, millimeter-wave grating spectrometer.It capable of obtaining manyspectral lines simultaneously because of its unprecedented broad bandwidth (185-305GHz). The bandpass covers the1mm atmospheric transmission window with a resolving power of 250-400. Z-Spec uses 160 silicon nitride micromeshbolometers cooled down to less than 100mK for background-limited performance. The unique capability of Z-Spec todetect multiple lines simultaneously allows us to obtain information efficiently on the physical and chemical conditionsof nearby Ultra-luminous Infrared Galaxies (ULIRGs) powered by starbursts or Active Galactic Nuclei. Here we reporton new millimeter-wave broadband data for ULIRGs acquired with Z-Spec and the noise performance and achievedsensitivity in observations with the CSO. We found that during the observations the noise scales with the atmosphericopacity and can be explained well by our sensitivity model, considering the photon noise originating from the sky andthe telescope, as well as the detector and electronics noise. The photon noise is found to dominate the total noise.