Optical and X-ray Studies of Ten X-ray Selected Cataclysmic Binaries

TL;DR

This study presents optical and X-ray observations of ten X-ray selected cataclysmic binaries, determining their orbital periods, pulsations, and classifications, including identifying several as intermediate polars and polars, and estimating their distances.

Contribution

First detailed optical and X-ray analysis of ten X-ray selected cataclysmic binaries, including orbital periods, pulsations, and classifications, with distance estimates for one object.

Findings

Eight objects have unambiguous orbital periods ranging from 87 min to 9.38 hr.

Six targets show coherent pulsations, indicating intermediate polars or polars.

Seven sources exhibit coherent oscillations in X-ray or optical, confirming their classification as intermediate polars.

Abstract

We report on ground-based optical observations of ten cataclysmic binaries that were discovered through their X-ray emission. Time-resolved radial velocity spectroscopy yields unambiguous orbital periods for eight objects and ambiguous results for the remaining two. The orbital periods range from 87 min to 9.38 hr. We also obtained time-series optical photometry for six targets, four of which have coherent pulsations. These periods are 1218 s for 1RXS J045707.4+452751, 628 s for AX J1740.2-2903, 477 s for AX J1853.3-0128, and 935 s for IGR J19267+1325. A total of seven of the sources have coherent oscillations in X-rays or optical, indicating that they are intermediate polars (DQ Herculis stars). Time-resolved spectroscopy of one object, Swift J2218.4+1925, shows that it is an AM Herculis star, or polar, and IGR J19552+0044 may also be in that class. For another object, Swift J0476.2-1611, we find an orbital period of 9.384 hr and detect the spectrum of the secondary star. The secondary's spectral contribution implies a distance of 900 (+190, -150) pc, where the error bars are estimated using a Monte Carlo technique to account for correlated uncertainties.