GPU-enabled searches for periodic signals of unknown shape

Abstract

Recent and future generation observatories will enable the study of variable astronomical phenomena through their time-domain capabilities. High temporal fidelity will allow for unprecedented investigations into the nature of variable objects — those objects that vary in brightness over time. A major bottleneck in data processing pipelines is constructing light curve solutions for catalogs of variable objects, as it is well-known that period finding algorithms are computationally expensive. Furthermore, there are many period finding algorithms that are often suited for specific science cases. In this paper, we present the first GPU-accelerated Super Smoother algorithm. Super Smoother is general purpose and uses cross-validation to fit line segments to a time series, and as such, is more computationally expensive than other algorithms, such as Lomb–Scargle. Because the algorithm requires making several scans over the input time series for a tested frequency, we also propose a novel generalized-validation variant of Super Smoother that only requires a single scan over the data. We compare the performance of our algorithms to analogous parallel multi-core CPU implementations on three catalogs of data, and show that it is generally advantageous to use the GPU algorithm over the CPU counterparts. Furthermore, we demonstrate that our single-pass variant of Super Smoother is roughly equally as accurate at finding correct period solutions as the original algorithm. Our software supports several features, such as batching the computation to eliminate the possibility of exceeding global memory on the GPU, processing a single object or batches of objects, and we allow for scaling the algorithm across multiple GPUs.