Rates, Flux Densities, and Spectral Indices of Meteor Radio Afterglows

TL;DR

This study analyzes meteor radio afterglows detected by LWA1 at low frequencies, characterizing their flux densities, spectral indices, and temporal evolution to predict their observability with other radio telescopes.

Contribution

It provides the first detailed spectral analysis of meteor radio afterglows across multiple frequencies and models their spectral evolution over time.

Findings

Spectral indices are time-variable and steepen over time.

Detected 124 meteor afterglows at multiple frequencies.

Predicted flux densities and detection rates for other low-frequency telescopes.

Abstract

Using the narrowband all-sky imager mode of the LWA1 we have now detected 30 transients at 25.6 MHz, 1 at 34 MHz, and 93 at 38.0 MHz. While we have only optically confirmed that 37 of these events are radio afterglows from meteors, evidence suggests that most, if not all, are. Using the beam-forming mode of the LWA1 we have also captured the broadband spectra between 22.0 and 55.0 MHz of four events. We compare the smooth, spectral components of these four events and fit the frequency dependent flux density to a power law, and find that the spectral index is time variable, with the spectrum steepening over time for each meteor afterglow. Using these spectral indices along with the narrow band flux density measurements of the 123 events at 25.6 and 38 MHz, we predict the expected flux densities and rates for meteor afterglows potentially observable by other low frequency radio telescopes.