VLBI observations of the G25.65+1.05 water maser superburst

TL;DR

This study documents a rare and intense water maser superburst in a star-forming region, revealing that the event was caused by the alignment of multiple maser regions along the line of sight, as observed through VLBI techniques.

Contribution

It provides the first detailed VLBI analysis of a water maser superburst, identifying the cause as superposition of multiple emitting regions.

Findings

Recorded a maser flux density of 1.2 x 10^4 Jy during the superburst.

Determined the superburst was caused by alignment of multiple maser regions.

Analyzed the spectral, structural, and temporal characteristics of the burst.

Abstract

This paper reports observations of a 22 GHz water maser `superburst' in the G25.65+1.05 massive star forming region, conducted in response to an alert from the Maser Monitoring Organisation (M2O). Very long baseline interferometry (VLBI) observations using the European VLBI Network (EVN) recorded a maser flux density of $1.2 \times 10^{4}$ Jy. The superburst was investigated in the spectral, structural and temporal domains and its cause was determined to be an increase in maser path length generated by the superposition of multiple maser emitting regions aligning in the line of sight to the observer. This conclusion was based on the location of the bursting maser in the context of the star forming region, its complex structure, and its rapid onset and decay.