The Excess Radio Background and Fast Radio Transients

TL;DR

This paper investigates whether fast radio transients, including FRBs, could significantly contribute to the excess radio background detected by ARCADE 2, providing estimates and models for their potential impact.

Contribution

It offers the first detailed estimates of the contribution of fast radio transients to the diffuse radio background, including a general framework applicable to future discoveries.

Findings

FRBs contribute negligibly to the radio background (6-7 orders of magnitude too small).

The developed models can be applied to any fast transient sources.

Parameter estimates identify conditions for transients to impact the radio background.

Abstract

In the last few years ARCADE 2, combined with older experiments, has detected an additional radio background, measured as a temperature and ranging in frequency from 22 MHz to 10 GHz, not accounted for by known radio sources and the cosmic microwave background. One type of source which has not been considered in the radio background is that of fast transients (those with event times much less than the observing time). We present a simple estimate, and a more detailed calculation, for the contribution of radio transients to the diffuse background. As a timely example, we estimate the contribution from the recently-discovered fast radio bursts (FRBs). Although their contribution is likely 6 or 7 orders of magnitude too small (though there are large uncertainties in FRB parameters) to account for the ARCADE~2 excess, our development is general and so can be applied to any fast transient sources, discovered or yet to be discovered. We estimate parameter values necessary for transient sources to noticeably contribute to the radio background.