Modeling the Galactic CV Distribution for the ChaMPlane Survey

TL;DR

This paper develops a detailed model of the distribution and detection rates of cataclysmic variables in the Galaxy, aiding survey design and interpretation, with implications for the ChaMPlane Survey.

Contribution

It introduces a comprehensive Galactic CV distribution model incorporating dust, gas, and luminosity functions, and provides predicted detection maps for current and future surveys.

Findings

Estimated CV local space density of 0.9^{+1.5}_{-0.5}*10^-5 pc^-3.

Created detailed maps of CV distribution across the Galactic plane.

Predicted detection rates as a function of survey limiting magnitude.

Abstract

For purposes of designing targeted cataclysmic variable (CV) detection surveys and interpreting results of other projects with many CV detections such as the ChaMPlane Survey, we have created a model of the CV distribution in the Galaxy. It is modeled as a warped, flared exponential disk with a gaussian vertical distribution. Extinction is based on a detailed Galactic dust and gas model. A luminosity function for CVs is also incorporated, based on a smoothed version of published data. We calculate predicted field detection rates as a function of the limiting magnitude expected for the detecting system (i.e. WIYN/Hydra or NOAO 4m/Mosaic). Monte-Carlo techniques are used to assess statistical fluctuations in these rates. We have created maps of the expected CV distribution for the full non-bulge Galactic plane (20<l<340, |b|<15) for use in both the ChaMPlane Survey and future CV surveys. Assuming a CV distribution with a scale height of 160 pc, the ChaMPlane observational result of 5 CVs in 13 northern fields is best fit by a CV local space density of 0.9^{+1.5}_{-0.5}*10^-5 pc^-3, with the range representing the 95% confidence interval.