Variability, flaring and coherence -- the complementarity of the maser and superradiance regimes

TL;DR

This paper explores how coherence phenomena, specifically maser radiation and superradiance, influence spectral line variability and flaring behavior in astrophysical sources, highlighting observational diagnostics to distinguish these regimes.

Contribution

It introduces superradiance as a complementary mechanism to maser action, explaining variability and flaring in spectral lines, with observational diagnostics to identify superradiance in astrophysical data.

Findings

Superradiance can explain rapid flaring in maser sources.

Observational diagnostics can distinguish between maser and superradiance regimes.

Superradiance accounts for different time-scales in multi-wavelength maser monitoring.

Abstract

We discuss the role that coherence phenomena can have on the intensity variability of spectral lines associated with maser radiation. We do so by introducing the fundamental cooperative radiation phenomenon of (Dicke's) superradiance and discuss its complementary nature to the maser action, as well as its role in the flaring behaviour of some maser sources. We will consider examples of observational diagnostics that can help discriminate between the two, and identify superradiance as the source of the latter. More precisely, we show how superradiance readily accounts for the different time-scales observed in the multi-wavelength monitoring of the periodic flaring in G9.62+0.20E.