Absolute Calibration of Diffuse Radio Surveys at 45 and 150 MHz

Abstract

We use EDGES measurements to determine scale and zero-level corrections to the diffuse radio surveys by Guzmán et al. at $45$ MHz and Landecker & Wielebinski at $150$ MHz. We find that the Guzmán et al. map requires a scale correction of $1.076\pm 0.034$ ($2\sigma$) and a zero-level correction of $-160\pm 78$ K ($2\sigma$) to best-fit the EDGES data. For the Landecker & Wielebinski map, the scale correction is $1.112\pm 0.023$ ($2\sigma$) and the zero-level correction is $0.7\pm 6.0$ K ($2\sigma$). The correction uncertainties are dominated by systematic effects, of which the most significant are uncertainty in the calibration of the EDGES receivers, antenna pointing, and tropospheric and ionospheric effects. We propagate the correction uncertainties to estimate the uncertainties in the corrected maps themselves and find that the $2\sigma$ uncertainty in the map brightness temperature is in the range $3.2-7.5\%$ for the Guzmán et al. map and $2.1-9.0\%$ for the Landecker & Wielebinski map, with the largest percent uncertainties occurring at high Galactic latitudes. The corrected maps could be used to improve existing diffuse low-frequency radio sky models, which are essential tools in analyses of cosmological $21$ cm observations, as well as to investigate the existence of a radio monopole excess above the cosmic microwave background and known Galactic and extragalactic contributions.

Accepted for publication in ApJ

References in corpus (17)

• Cosmology at Low Frequencies: The 21 cm Transition and the High-Redshift Universe
• PolyChord: nested sampling for cosmology
• Signature of Excess Radio Background in the 21-cm Global Signal and Power Spectrum
• All-sky Galactic radiation at 45 MHz and spectral index between 45 and 408 MHz
• Results from EDGES High-Band: I. Constraints on Phenomenological Models for the Global $21$ cm Signal
• Simulating polarized Galactic synchrotron emission at all frequencies, the Hammurabi code
• The contribution of the Unresolved Extragalactic Radio Sources to the Brightness Temperature of the sky
• Improved Measurement of the Spectral Index of the Diffuse Radio Background Between 90 and 190 MHz
• Spectral Index of the Diffuse Radio Background Between 50 and 100 MHz
• SARAS measurement of the Radio Background at long wavelengths
• Quantifying Ionospheric Effects on Global 21-cm Observations
• GMOSS: All-sky model of spectral radio brightness based on physical components and associated radiative processes
• Radiometric Measurements of Electron Temperature and Opacity of Ionospheric Perturbations
• Cosmic backgrounds due to the formation of the first generation of supermassive black holes
• TRIS III: the diffuse galactic radio emission at $\delta =+42^{\circ }$
• On the impact of large angle CMB polarization data on cosmological parameters
• Cosmological origin of anomalous radio background

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