Discovering periodic and repeating nuclear transients in the XMM-Newton archives
Natalie A. Webb, Vincent Foustoul, Robbie Webbe, Matteo Bachetti, Erwan Quintin, Laurent Michel
TL;DR
Webb et al. analyze the XMM-Newton archives to illuminate nuclear transients around massive black holes. They review major X-ray catalogues (4XMM-DR14, XMMSL3, XMMSL Slew, OM UV data) and demonstrate how long-baseline data reveal tidal disruption events, partial TDEs, quasi-periodic eruptions, and massive black hole binaries, among others. The authors introduce a periodicity search in galaxy centers and present near real-time transient alerts through the STONKS pipeline, including four candidate TDEs identified from fading light curves. Together, the work showcases the power of archival X-ray data for uncovering rare, long-term nuclear phenomena and points to future opportunities with the upcoming 5XMM catalogue for improved classification and follow-up.
Abstract
The regions around massive black holes can show X-ray variability on timescales from seconds to decades. Observing many black holes over different timescales can enhance our chances of detecting variability coming from (partial) tidal disruption events, massive black hole binaries, changing state AGN, blazar activity and much more. X-ray catalogues with hundreds of thousands of detections are treasure troves of such sources, which require innovative methods to identify these black holes. We present the current XMM-Newton catalogues available and describe several examples of tidal disruption events (TDEs) and quasi-periodic eruption sources that have been found whilst mining this data. We describe preliminary work on a search for periodic variables in the XMM-Newton EPIC archival data, with the example of finding new massive black hole binaries. We also describe the STONKS pipeline that is now in the XMM-Newton automatic reduction pipeline and the near real-time alert system that allows the follow-up of new and fading transients. We provide examples of fading sources that are newly identified candidate TDEs.