# A connection between accretion states and the formation of ultra-relativistic outflows in a neutron star X-ray binary

## TL;DR

This study links the ejection of ultra-relativistic flows in a neutron star binary to specific X-ray oscillations, providing new insights into jet formation mechanisms at high accretion rates.

## Contribution

It establishes a tentative connection between ultra-relativistic outflows and particular X-ray oscillations in Sco X-1, a step forward in understanding jet physics.

## Key findings

- Ultra-relativistic flows are associated with specific X-ray QPOs.
- Mildly relativistic outflows correlate with broad band noise.
- First observed link between unseen flows and accretion states.

## Abstract

The nearby accreting neutron star binary Sco X-1 is the closest example of ongoing relativistic jet production at high Eddington ratios. Previous radio studies have revealed that alongside mildly relativistic, radio-emitting ejecta, there is at times a much faster transfer of energy from the region of the accretion flow along the jet. The nature of this ultrarelativistic flow remains unclear and while there is some evidence for a similar phenomenon in other systems which might contain neutron stars, it has never been observed in a confirmed black hole system. We have compared these previous radio observations with a new analysis of simultaneous X-ray observations which were performed with the RXTE mission. We find that the ejection of the ultra-relativistic flow seems to be associated with the simultaneous appearance of two particular types of quasi-periodic oscillations in the X-ray power spectrum. In contrast, the mildly relativistic, radio-emitting outflows may be associated with flat-topped broad band noise in the X-ray power spectrum. This is the first time a link, albeit tentative, has been found between these mysterious unseen flows and the accretion flow from which they are launched.