Space and Time Algorithm for
Transients in X-rays (STATiX)
The X-ray universe is full of brief and faint outbursts — sudden changes in brightness caused by phenomena such as black hole accretion, neutron star activity, or stellar flares. Many of these events are so short or weak that they disappear when observations are combined into a single image. The new algorithm STATiX (Space and Time Algorithm for Transients in X-rays) was developed to uncover these hidden events by analysing X-ray data simultaneously in space and time, rather than in static images alone.
STATiX treats an X-ray observation as a three-dimensional cube, with two dimensions for position and one for time. By examining this cube, the algorithm can detect real variations in brightness as they occur. It builds on advanced tools from image and signal processing — particularly the Multi-Scale Variance Stabilisation Transform — to distinguish genuine signals from background noise. This makes STATiX highly sensitive to both persistent X-ray sources and short-lived transients that traditional methods often miss.
Quasi-Periodic Eruption in GSN069
Light curve from the three XMM-Newton EPIC cameras (pn, MOS1, MOS2) of the galaxy GSN 069, showing a series of quasi-periodic X-ray eruptions caused by matter accreting onto the central black hole. These rare “QPEs” are among the most intriguing transient phenomena revealed by XMM-Newton observations.
Stellar Flares Detected by STATiX
Examples of stellar flares identified by STATiX in XMM-Newton data. These rapid and intense brightenings, driven by magnetic activity on the surfaces of stars, represent the most common class of transient sources uncovered by the algorithm.
STATiX is implemented as a Python package and can now process data from all three XMM-Newton EPIC cameras: pn, MOS1, and MOS2. It can operate directly on standard XMM-Newton data products, or, when needed, generate them automatically through the mission’s Science Analysis Software (SAS). The algorithm is fully optimized for XMM-Newton data but its design can be adapted for future X-ray observatories.
The STATiX team has now applied this method to the entire XMM-Newton archive, performing a systematic search for transient sources across more than two decades of observations. By combining spatial and temporal analysis, STATiX opens a powerful new window on the dynamic X-ray sky, allowing astronomers to study faint, fast events that were previously undetectable. Its public release provides the community with a versatile tool to explore variability in X-ray data and to uncover new classes of high-energy phenomena.
