EXTraS: Exploring the X-ray Transient and variable Sky

Andrea de Luca, INAF - IASF Milano — 22.02.2021

Temporal variability in flux and spectral shape is ubiquitous in the X-ray sky and carries crucial information about the sources' nature and emission physics. The EPIC instrument onboard the XMM-Newton observatory is the most powerful tool to study variability even in faint sources. It collects, each day, a large amount of information about hundreds of new serendipitous sources, but the resulting huge (and growing) dataset is largely unexplored in the time domain.

The EXTraS project (Exploring the X-ray Transient and variable Sky) systematically extracted all temporal domain information buried in the XMM-Newton archive. This included a search and characterisation of variability, both periodic and aperiodic, in hundreds of thousands of sources spanning more than eight orders of magnitude in time scale and six orders of magnitude in flux, as well as a search for fast transients, missed by standard image analysis. All results, products and software tools have been released to the community in a public archive. A science gateway has also been implemented, to allow users to run remotely the EXTraS analysis on recent XMM datasets.

I will give details on the data analysis carried out within EXTraS, I will describe its results and products and I will show a selection of scientific results.