Holographic Beam Measurements of the Canadian Hydrogen Intensity Mapping Experiment (CHIME)
arXiv:2408.00172 · doi:10.3847/1538-4357/ad8133
Abstract
We present the first results of the holographic beam mapping program for the Canadian Hydrogen Intensity Mapping Experiment (CHIME). We describe the implementation of the holographic technique as adapted for CHIME, and introduce the processing pipeline which prepares the raw holographic timestreams for analysis of beam features. We use data from six bright sources across the full 400-800\,MHz observing band of CHIME to provide measurements of the co-polar and cross-polar beam response of CHIME in both amplitude and phase for the 1024 dual-polarized feeds instrumented on CHIME. In addition, we present comparisons with independent probes of the CHIME beam which indicate the presence of polarized beam leakage in CHIME. Holographic measurements of the CHIME beam have already been applied in science with CHIME, e.g. in estimating detection significance of far sidelobe FRBs, and in validating the beam models used for CHIME's first detections of \tcm emission (in cross-correlation with measurements of large-scale structure from galaxy surveys and the Lyman- forest). Measurements presented in this paper, and future holographic results, will provide a unique data set to characterize the CHIME beam and improve the experiment's prospects for a detection of BAO.
arXiv commentsubmitted to ApJ
References in corpus (29)
- SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
- Array Programming with NumPy
- HEALPix -- a Framework for High Resolution Discretization, and Fast Analysis of Data Distributed on the Sphere
- TEMPO2, a new pulsar timing package. I: Overview
- The CHIME Fast Radio Burst Project: System Overview
- Bright Source Subtraction Requirements For Redshifted 21 cm Measurements
- Measurement of 21 cm brightness fluctuations at z ~ 0.8 in cross-correlation
- A Per-Baseline, Delay-Spectrum Technique for Accessing the 21cm Cosmic Reionization Signature
- Determination of z~0.8 neutral hydrogen fluctuations using the 21 cm intensity mapping auto-correlation
- Toward Epoch of Reionization Measurements with Wide-Field Radio Observations
- Canadian Hydrogen Intensity Mapping Experiment (CHIME) Pathfinder
- Radio Foregrounds for the 21cm Tomography of the Neutral Intergalactic Medium at High Redshifts
- A Method for 21cm Power Spectrum Estimation in the Presence of Foregrounds
- Coaxing Cosmic 21cm Fluctuations from the Polarized Sky using m-mode Analysis
- Lack of clustering in low-redshift 21-cm intensity maps cross-correlated with 2dF galaxy densities
- Foregrounds in Wide-Field Redshifted 21 cm Power Spectra
- Foregrounds for 21cm Observations of Neutral Gas at High Redshift
- The 21 centimeter emission from the reionization epoch: extended and point source foregrounds
- HI constraints from the cross-correlation of eBOSS galaxies and Green Bank Telescope intensity maps
- Detection of Cosmological 21 cm Emission with the Canadian Hydrogen Intensity Mapping Experiment
- A Scalable Correlator Architecture Based on Modular FPGA Hardware, Reuseable Gateware, and Data Packetization
- The CHIME Pulsar Project: System Overview
- First Detection of Cosmic Structure in the 21-cm Intensity Field
- A compression scheme for radio data in high performance computing
- DAYENU: A Simple Filter of Smooth Foregrounds for Intensity Mapping Power Spectra
- A Radio-Frequency-over-Fiber link for large-array radio astronomy applications
- Holographic Beam Mapping of the CHIME Pathfinder Array
- Using the Sun to Measure the Primary Beam Response of the Canadian Hydrogen Intensity Mapping Experiment
- Gain and Polarization Properties of a Large Radio Telescope from Calculation and Measurement: The John A. Galt Telescope