Characterizing Three Candidate Magnetic CVs from SDSS: XMM-Newton and Optical Follow-up Observations

Abstract

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 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 a period around 4 hrs, though neither dataset 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 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.

12 pages, 9 figures, accepted for publication in the Astronomical Journal

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Cited by in corpus (9)

• SDSS unveils a population of intrinsically faint cataclysmic variables at the minimum orbital period
• X-Ray-Emitting Stars Identified from the ROSAT All-Sky Survey and the Sloan Digital Sky Survey
• Accreting pulsars: mixing-up accretion phases in transitional systems
• Quasi-periodic oscillations in accreting magnetic white dwarfs I. Observational constraints in X-ray and optical
• IPHAS J062746.41+014811.3: a deeply eclipsing intermediate polar
• Optical identification of X-ray source 1RXS J180431.1-273932 as a magnetic cataclysmic variable
• XMM-Newton and Optical Observations of Cataclysmic Variables from SDSS
• Two new magnetic cataclysmic variables discovered in the 3XMM catalogue
• Search for magnetic accretion in SW Sextantis systems