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Traditionally, new pulsars are identified from diagnostic images by humans (such as the new pulsars found in the LOFAR pilot surveys). The AI mimics these human experts and distinguishes pulsars from noise and interference by looking for patterns from candidate plots. Different from other pulsar selection programs which searched for expected patterns, the PICS AI is taught the salient features of different pulsars from a set of human-labeled candidates through machine learning.
The training candidates are collected from the Pulsar Arecibo L-band Feed Array Survey, which is carried out by a team including ASTRON's Jason Hessels and Joeri van Leeuwen. The information from each pulsar candidate is synthesized in four diagnostic plots, which consist of image data with up to thousands of pixels. The AI takes these data from each candidate as its input and uses thousands of such candidates to train its 9000 neurons. The deep neural networks in this AI system grant it superior ability in recognizing various types of pulsars as well as their harmonic signals.
The performance of this system can be improved over time as more training data are accumulated. This AI system has been integrated into the PALFA survey pipeline and has discovered six new pulsars to date!