Calibration Error in 21-centimeter Global Spectrum Experiments
arXiv:2405.17742 · doi:10.3390/universe10060236
Abstract
The redshifted 21 cm line signal is a powerful probe of the cosmic dawn and the epoch of reionization. The global spectrum can potentially be detected with a single antenna and spectrometer. However, this measurement requires an extremely accurate calibration of the instrument to facilitate the separation of the 21 cm signal from the much brighter foregrounds and possible variations in the instrument response. Understanding how the measurement errors propagate in a realistic instrument system and affect system calibration is the focus of this work. We simulate a 21 cm global spectrum observation based on the noise wave calibration scheme. We focus on how measurement errors in reflection coefficients affect the noise temperature and how typical errors impact the recovery of the 21 cm signal, especially in the frequency domain. Results show that for our example set up, a typical vector network analyzer (VNA) measurement error in the magnitude of the reflection coefficients of the antenna, receiver, and open cable, which are 0.001, 0.001, and 0.002 (linear), respectively, would result in a 200 mK deviation on the detected signal, and a typical measurement error of 0.48 degree, 0.78 degree, or 0.15 degree in the respective phases would cause a 40 mK deviation. The VNA measurement error can greatly affect the result of a 21 cm global spectrum experiment using this calibration technique, and such a feature could be mistaken for or be combined with the 21 cm signal
arXiv comment29 pages, 20 figures
References in corpus (33)
- Cosmology at Low Frequencies: The 21 cm Transition and the High-Redshift Universe
- An absorption profile centred at 78 megahertz in the sky-averaged spectrum
- 21-cm Tomography of the Intergalactic Medium at High Redshift
- A New Calculation of the Recombination Epoch
- Possible interaction between baryons and dark-matter particles revealed by the first stars
- A model of diffuse Galactic Radio Emission from 10 MHz to 100 GHz
- How exactly did the Universe become neutral?
- The Spin-Kinetic Temperature Coupling and the Heating Rate due to Lyman Alpha Scattering before Reionization: Predictions for 21cm Emission and Absorption
- Enhanced global signal of neutral hydrogen due to excess radiation at cosmic dawn
- Concerns about Modelling of the EDGES Data
- Modeling the Radio Background from the First Black Holes at Cosmic Dawn: Implications for the 21 cm Absorption Amplitude
- A lower limit of dz > 0.06 for the duration of the reionization epoch
- Charting the Parameter Space of the Global 21-cm Signal
- Design and characterization of the Large-Aperture Experiment to Detect the Dark Age (LEDA) radiometer systems
- Probing the Dark Ages at Z~20: The SCI-HI 21 cm All-Sky Spectrum Experiment
- BIGHORNS - Broadband Instrument for Global HydrOgen ReioNisation Signal
- A Ground Plane Artifact that Induces an Absorption Profile in Averaged Spectra from Global 21-cm Measurements - with Possible Application to EDGES
- Toward Empirical Constraints on the Global Redshifted 21 cm Brightness Temperature During the Epoch of Reionization
- The Rise of the First Stars: Supersonic Streaming, Radiative Feedback, and 21-cm Cosmology
- Results from EDGES High-Band: I. Constraints on Phenomenological Models for the Global cm Signal
- How well do we understand cosmological recombination?
- SARAS: a precision system for measurement of the Cosmic Radio Background and signatures from the Epoch of Reionization
- SARAS 2: A Spectral Radiometer for probing Cosmic Dawn and the Epoch of Reionization through detection of the global 21 cm signal
- Calibration of the EDGES High-Band Receiver to Observe the Global 21-cm Signature from the Epoch of Reionization
- Absolute calibration of a wideband antenna and spectrometer for sky noise spectral index measurements
- The 21cm Signature of the First Stars
- A Space-Based Observational Strategy for Characterizing the First Stars and Galaxies Using the Redshifted 21-cm Global Spectrum
- SARAS 3 CD/EoR Radiometer: Design and Performance of the Receiver
- Matter temperature after cosmological recombination
- Assessment of the Projection-induced Polarimetry Technique for Constraining the Foreground Spectrum in Global 21 cm Cosmology
- Radiometric Measurements of Electron Temperature and Opacity of Ionospheric Perturbations
- Bayesian noise wave calibration for 21-cm global experiments
- One-Port Direct/Reverse Method for Characterizing VNA Calibration Standards
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- RHINO: A large horn antenna for detecting the 21cm global signal
- RFSoC receiver calibration system for 21-cm global spectrum experiments from space: The CosmoCube case
- Accounting for Noise and Singularities in Bayesian Calibration Methods for Global 21-cm Cosmology Experiments
- Forecast measurement of the 21 cm global spectrum from Lunar orbit with the Vari-Zeroth-Order Polynomial (VZOP) method