The Accretion Flow - Discrete Ejection Connection in GRS 1915+105

TL;DR

This study provides precise timing of a discrete ejection in GRS 1915+105, showing that increased X-ray flux occurs hours before ejection and persists within about 22 minutes, linking accretion activity to jet ejections.

Contribution

It offers the highest temporal resolution measurement of the X-ray and ejection connection, demonstrating that small-scale ejections share similar accretion physics with larger flares.

Findings

X-ray flux increases 2-4 hours before ejection

Ejection time determined within 41-minute precision

X-ray spike persists within 22 minutes of ejection

Abstract

The microquasar GRS~1915+105 is known for its spectacular discrete ejections. They occur unexpectedly, thus their inception escapes direct observation. It has been shown that the X-ray flux increases in the hours leading up to a major ejection. In this article, we consider the serendipitous interferometric monitoring of a modest version of a discrete ejection described in Reid et al. (2014) that would have otherwise escaped detection in daily radio light curves. The observation begins $\sim 1$ hour after the onset of the ejection, providing unprecedented accuracy on the estimate of the ejection time. The astrometric measurements allow us to determine the time of ejection as $\rm{MJD}\, 56436.274^{+0.016}_{-0.013}$, i.e., within a precision of 41 minutes (95\% confidence). Just like larger flares, we find that the X-ray luminosity increases in last 2 - 4 hours preceding ejection. Our finite temporal resolution indicates that this elevated X-ray flux persists within $21.8^{+22.6}_{-19.1}$ minutes of the ejection with 95\% confidence, the highest temporal precision of the X-ray - superluminal ejection connection to date. This observation provides direct evidence that the physics that launches major flares occurs on smaller scales as well (lower radio flux and shorter ejection episodes). The observation of a X-ray spike prior to a discrete ejection, although of very modest amplitude suggests that the process linking accretion behavior to ejection is general from the smallest scales to high luminosity major superluminal flares.