Characterizing Three Candidate Magnetic Cataclysmic Variables From SDSS: XMM-Newton and Optical Follow-Up Observations

摘要

In the latest in our series of papers on XMM-Newton and ground-based optical follow-up of new candidate magnetic cataclysmic variables (mCVs) found in the Sloan Digital Sky Survey, we report classifications of three systems: SDSS J144659.95+025330.3, SDSS J205017.84 053626.8, and SDSS J210131.26+105251.5. Both the X-ray and optical fluxes of SDSS J1446+02 are modulated on a period of 48:7 0:5 minutes, with the X-ray modulation showing the characteristic energy dependence of photoelectric absorption seen in many intermediate polars (IP). A longer period modulation and radial velocity variation is also seen at around 4 hr, although neither data set is long enough to constrain this longer, likely orbital, period well. SDSS J2050 05 appears to be an example of the most highly magnetized class of mCV, a diskless, stream- fed polar. Its 1.57 hr orbital period is well constrained via optical eclipse timings; in the X-ray it shows both eclipses and an underlying strong, smooth modulation. In this case broadly phase resolved spectral fits indicate that this change in flux is the result of a varying normalization of the dominant component (a 41 keV MEKAL plasma), plus the addition of a partial covering absorber during the lower flux interval. SDSS J2101+10 is a more perplexing system to categorize: its X-ray and optical fluxes exhibit no large periodic modulations; there are only barely detectable changes in the velocity structure of its optical emission lines; the X-ray spectra require only absorption by the interstellar medium; and the temperatures of the MEKAL fits are low, with maximum temperature components of either 10 or 25 keV. We conclude that SDSS J2101+10 cannot be an IP, nor likely a polar, but is rather most likely a disk accretor a low-inclination SW Sex star.