The eROSITA instrument onboard the SRG satellite provides a unique opportunity
for discovering transients in its X-ray All Sky survey data. There are many
classes of transients known to emit in X-rays, ranging from flares from active
stars to fast blazar variability. By necessity, I will highlight a few such
source classes and the open science questions that will benefit tremdously from
the...
The study of massive stars exploding as supernovae has seen a major breakthrough in recent years, with modern surveys making the detection and exploration of supernova explosions within a day of stellar core collapse possible. With its extremely wide field of view and mature infrastructure of integrated hardware, software and operations, the Zwicky Transient Facility (ZTF) has made such...
X-ray observations of Tidal Disruptions Events (TDEs) are a unique probe of the physics of accretion around supermassive black holes, as they are thought to transition from super- to sub-Eddington accretion on timescales of months/years. The first TDE candidates were found in the X-rays with the ROSAT All-Sky Survey, but, today, most of our candidates are found in the optical. While optical...
Due to eROSITA’s cadence and its 30-fold increased sensitivity in the soft X-ray band relative to ROSAT, eROSITA promises to detect 1000s of tidal disruption event (TDE) candidates during its all sky survey phase. I will present our machine-learning assisted approach for identifying TDE candidates amongst the millions of X-ray sources in eROSITA's source catalogues, and selected early results...
Almost 200 changing-look AGN/quasars are currently known showing significant spectroscopic and photometric variability on timescales of months to years. Although initially discovered by serendipity, systematic searches of archival survey data, such as SDSS, Pan-STARRS, and CRTS, have identified such sources in significant numbers. Ongoing time domain sky surveys, such as ZTF, which cover the...
During its PV phase eROSITA observed a ~100 deg2 field to the final depth expected after eight all-sky scans. The XMM Atlas survey is covered in this field. Between these data sets, we search for dramatic flux changes in AGN which would indicate AGN ignition/shut-down. I will present a few candidate events. We will extend this work using the data of all individual eight all-sky surveys by...
The Zwicky Transient Facility (ZTF) started science operation in March 2018. 40% of ZTF observing time is dedicated to two public surveys: one covering the entire Northern sky every three nights in g and r passbands and one visiting the Galactic Plane every night in g and r. In addition to the public Galactic Plane survey, ZTF has conducted a dedicated high-cadence survey of selected Galactic...
Ultraluminous X-ray sources are powerful extra-nuclear sources of X-rays found in nearby galaxies, which in most cases are believed to be powered by super-Eddington accretion onto neutron stars and black holes. While most known ULXs are persistent sources, recently some new sources have been found that appear to come and go. I will present results from a systematic search for these transient...
XMM-Newton supports currently nine joint programs and observes about 30% of its high priority targets simultaneously with other facilities. In addition, the observing program shows and exceptional high amount of TOO observations in comparison to other large observatory class mission. The talk describes the policy for joint programs and TOO and reflects on the potential for synergies with eROSITA.
