A Deep Learning Approach for Active Anomaly Detection of Extragalactic Transients
This addresses the challenge for astronomers in allocating limited follow-up resources to study rare events in real-time, representing an incremental improvement in anomaly detection methods for astrophysics.
The paper tackles the problem of identifying rare astronomical transients from large surveys like the Rubin Observatory by developing a variational recurrent autoencoder with an isolation forest for anomaly scoring, achieving a pure sample of rare transients with about 95% purity and enabling early detection before peak brightness.
There is a shortage of multi-wavelength and spectroscopic followup capabilities given the number of transient and variable astrophysical events discovered through wide-field, optical surveys such as the upcoming Vera C. Rubin Observatory. From the haystack of potential science targets, astronomers must allocate scarce resources to study a selection of needles in real time. Here we present a variational recurrent autoencoder neural network to encode simulated Rubin Observatory extragalactic transient events using 1% of the PLAsTiCC dataset to train the autoencoder. Our unsupervised method uniquely works with unlabeled, real time, multivariate and aperiodic data. We rank 1,129,184 events based on an anomaly score estimated using an isolation forest. We find that our pipeline successfully ranks rarer classes of transients as more anomalous. Using simple cuts in anomaly score and uncertainty, we identify a pure (~95% pure) sample of rare transients (i.e., transients other than Type Ia, Type II and Type Ibc supernovae) including superluminous and pair-instability supernovae. Finally, our algorithm is able to identify these transients as anomalous well before peak, enabling real-time follow up studies in the era of the Rubin Observatory.