# Maser Flare Simulations from Oblate and Prolate Clouds

## TL;DR

This paper uses numerical models to study how the shape and rotation of maser clouds affect their flaring variability, revealing potential observational differences between oblate and prolate clouds and limitations of rotation as a flare mechanism.

## Contribution

It introduces a detailed numerical analysis of maser flare variability from rotating spheroidal clouds, considering different shapes, saturation levels, and rotation axes, which was not previously explored.

## Key findings

- Flares from rotation have long timescales of years and modest variability indices.
- Rotation-induced flares can be aperiodic or quasi-periodic.
- Rotation is unlikely to explain short-term or strictly periodic maser variability.

## Abstract

We investigated, through numerical models, the flaring variability that may arise from the rotation of maser clouds of approximately spheroidal geometry, ranging from strongly oblate to strongly prolate examples. Inversion solutions were obtained for each of these examples over a range of saturation levels from unsaturated to highly saturated. Formal solutions were computed for rotating clouds with many randomly chosen rotation axes, and corresponding averaged maser light curves plotted with statistical information. The dependence of results on the level of saturation and on the degree of deformation from the spherical case were investigated in terms of a variability index and duty cycle. It may be possible to distinguish observationally between flares from oblate and prolate objects. Maser flares from rotation are limited to long timescales (at least a few years) and modest values of the variability index ($\lesssim 100$), and can be aperiodic or quasi-periodic. Rotation is therefore not a good model for H$_2$O variability on timescales of weeks to months, or of truly periodic flares.