EP-FXT sources: a quick-look database and real-time source search toolkit

Purpose The Einstein Probe (EP) is a space X-ray mission dedicated to the time-domain astrophysics, aiming to discover high-energy transients and monitor variable objects. As a principal scientific payload onboard EP, the Follow-up X-ray Telescope (FXT) mainly responses for prompt and deep follow-up observations of the triggered targets by EP-WXT and discovers and characterizes X-ray transients, particularly faint or distant X-ray transients. Since these transient signals fade rapidly or evolve dramatically, a fast and reliable analysis of the FXT data is essential to discover them and trigger timely and efficient follow-up observations, which is important to identify the nature of these sources.
Methods To address this issue, we develop a real-time source search toolkit to automatically process EP-FXT observations in real time, detecting all the sources in the field of view of FXT, extracting their scientific information, and searching for transients and bursts. Accordingly, the toolkit consists of three modules: source detection, source information extraction, and source identification.
Results The toolkit outcomes a quick-look database: 1) a series of high-level scientific products for every observed source, such as the position, count rate, flux, variability amplitude, hardness, light curve, an absorbed powerlaw or blackbody model fitted spectrum, and the power density spectrum; 2) transients and bursts; 3) source list; 4) sky map. As the software is automatically running, this quick-look database is continuously updated.
Conclusion The real-time source search toolkit can process all the observed data and effectively meets the fast source search requirements of FXT.