  Modern X-ray telescopes have detected hundreds of thousands of X-ray sources
in the universe. However, current methods to classify these sources using the
X-ray data themselves suffer problems - detailed X-ray spectroscopy of
individual sources is too time-consuming, while hardness ratios often lack
accuracy, and can be difficult to use effectively. These methods fail to use
the power of X-ray CCD detectors to identify X-ray emission lines and
distinguish line-dominated spectra (from chromospherically active stars,
supernova remnants, etc.) from continuum-dominated ones (e.g., compact objects
or active galactic nuclei [AGN]). In this paper, we probe the use of artificial
neural networks (ANN) in differentiating Chandra spectra of young stars in the
Chandra Orion Ultradeep Project (COUP) survey from AGN in the Chandra Deep
Field South (CDFS) survey. We use these surveys to generate 100,000 artificial
spectra of stars and AGN and train our ANN models to separate the two kinds of
spectra. We find that our methods reach an accuracy of approx. 92% in
classifying simulated spectra of moderate-brightness objects in typical
exposures, but their performance slightly decreases on the observed COUP and
CDFS spectra (approx. 91%), due in large part to the relatively high background
of these long-exposure datasets. We also investigate the performance of our
methods with changing properties of the spectra such as the net source counts,
the relative contribution of background, the absorption column of the sources,
etc. We conclude that these methods have substantial promise for application to
large X-ray surveys.
