Z45: A New 45-GHz Band Dual-Polarization HEMT Receiver for the NRO 45-m Radio Telescope

Abstract

We developed a dual-linear-polarization HEMT (High Electron Mobility Transistor) amplifier receiver system of the 45-GHz band (hereafter Z45), and installed it in the Nobeyama 45-m radio telescope. The receiver system is designed to conduct polarization observations by taking the cross correlation of two linearly-polarized components, from which we process full-Stokes spectroscopy. We aim to measure the magnetic field strength through the Zeeman effect of the emission line of CCS ($J_N=4_3-3_2$) toward pre-protostellar cores. A linear-polarization receiver system has a smaller contribution of instrumental polarization components to the Stokes $V$ spectra than that of the circular polarization system, so that it is easier to obtain the Stokes $V$ spectra. The receiver has an RF frequency of 42 $-$ 46 GHz and an intermediate frequency (IF) band of 4$-$8 GHz. The typical noise temperature is about 50 K, and the system noise temperature ranges from 100 K to 150K over the frequency of 42 $-$ 46 GHz. The receiver system is connected to two spectrometers, SAM45 and PolariS. SAM45 is a highly flexible FX-type digital spectrometer with a finest frequency resolution of 3.81 kHz. PolariS is a newly-developed digital spectrometer with a finest frequency resolution of 60 Hz, having a capability to process the full-Stokes spectroscopy. The Half Power Beam Width (HPBW) of the beam was measured to be 37$"$ at 43 GHz. The main beam efficiency of the Gaussian main beam was derived to be 0.72 at 43 GHz. The SiO maser observations show that the beam pattern is reasonably round at about 10 \% of the peak intensity and the side-lobe level was less than 3 \% of the peak intensity. Finally, we present some examples of astronomical observations using Z45.

32 pages, 12 figures, accepted by PASJ

References in corpus (2)

• Cluster Formation Triggered by Filament Collisions in Serpens South
• Molecular Line Observations of a Carbon-Chain-Rich Core L492

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• Spectral Tomography for the Line-of-Sight Structures of the Taurus Molecular Cloud 1
• Discovery of CCS Velocity-Coherent Substructures in the Taurus Molecular Cloud 1
• ${}^{13}$C isotopic fractionation of HC${}_3$N in two starless cores: L1521B and L134N (L183)
• Chemical Diversity in Three Massive Young Stellar Objects associated with 6.7 GHz CH${}_3$OH Masers
• A Statistical Study of Massive Cluster-Forming Clumps
• Observations of Cyanopolyynes toward Four High-Mass Star-Forming Regions Containing Hot Cores
• An International Survey of Front-End Receivers and Observing Performance of Telescopes for Radio Astronomy
• Discovery of Infalling Motion with Rotation of the Cluster-Forming Clump S235AB and Its Implication to the Clump Structures
• First clear detection of the CCS Zeeman splitting toward the pre-stellar core, Taurus Molecular Cloud-1
• Discovery of CO Clouds Associated with the X-ray Jets of SS 433: Evidence for Shock-Cloud Interaction Enhancing Nonthermal X-ray Emission