the field that could be either additional contaminants unaccounted for by the simulations, and/or young stellar objects found outside the famous Carina clusters. In the former case, our underestimation of the Galactic stellar contamination population could be due to un-modeled young MS stars associated with Galactic spiral arm toward Carina, or background field stars with distances $>5$ kpc (§\[contaminants\_stellar\_section\]). In the latter case, we have an indication for the presence of a widely distributed population of young stars in the Carina complex.

Summary {#summary_section}
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This work describes simulations of X-ray-emitting source populations that will appear in high-resolution [*Chandra X-ray Observatory*]{} studies along the Galactic Plane. The effort is particularly relevant to discriminating PMS stars in star forming regions from Galactic field star and extragalactic contamination. Our simulations account for two X-ray classes: extragalactic sources (primarily AGNs) seen through the Galactic disk and Galactic field stars (main sequence and giants from types F to M) distributed throughout the disk. The simulations are based on a variety of technical considerations (§ \[contaminants\_main\_section\]): use of a Galactic population synthesis model and measured X-ray luminosity functions to obtain field star X-ray source distributions; convolution of realistic contaminant X-ray intensity and spectral distributions through 