X-Ray Binaries in the ZTF Alert Stream

The Zwicky Transient Facility (ZTF) detects hundreds of thousands of variable, transient, and moving sources per night. These sources are packaged into alerts and publicly released via a Kafka stream. We created a pipeline to search this stream for outbursting X-ray binaries (XRBs) by crossmatching the positions of the alerts to catalogued X-ray sources, and then analyzing the 30 day lightcurve of matched alerts by thresholding on differences with an 8-day exponentially weighted moving average. In addition to the year-long live search for XRBs, we ran the pipeline over three years of ZTF archival data. We discuss the implication for the rate of optically-detectable XRB outbursts in the galaxy.