Identifying Transients in the Dark Energy Survey using Convolutional Neural Networks

The ability to discover new transient candidates via image differencing without direct human intervention is an important task in observational astronomy. For these kind of image classification problems, machine Learning techniques such as Convolutional Neural Networks (CNNs) have shown remarkable success. In this work, we present the results of an automated transient candidate identification on images with CNNs for an extant dataset from the Dark Energy Survey Supernova program (DES-SN), whose main focus was on using Type Ia supernovae for cosmology. By performing an architecture search of CNNs, we identify networks that efficiently select non-artifacts (e.g. The CNNs also help us identify a subset of mislabeled images. Performing a relabeling of the images in this subset, the resulting classification with CNNs is significantly better than previous results, lowering the false positive rate by 27% at a fixed missed detection rate of 0.05. INTRODUCTION A major aspect of observational astronomy is the "survey" which involves the wholesale mapping of various regions of the sky to create catalogs which are subsequently mined for scientifically important astronomical objects. We refer to a transient candidate as the detection on a single image of a new or varying source with respect to a previously taken reference image, regardless of its astrophysical nature since at this stage its classification is unknown and will remain so until further data is taken (spectroscopy and/or additional photometry). Some examples of such transient candidates are solar system objects, supernovae, active galactic nuclei, variable stars, and neutron star mergers, etc. Since some of these events are quite rare and will fade rapidly, it is often important to trigger follow-up observations immediately to glean their underlying nature and discover new physics. Hence, identifying transient candidates in images quickly and efficiently is very important so as not to waste precious, and expensive, follow-up resources. For many years this process was conducted by manual inspection of images by humans.