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 \pm 0.5 min , with the X-ray modulation showing the characteristic energy dependence of photo-electric absorption seen in many intermediate polars ( IP ) .
A longer period modulation and radial velocity variation is also seen at around 4 hrs , though neither dataset 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 disk-less , 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 ) , 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 can not be an IP , nor likely a polar , but is rather most likely a disc accretor– a low inclination SW Sex star .