XMM-Newton and Optical Follow-up Observations of Three New Polars from the Sloan Digital Sky Survey

Abstract

We report follow-up XMM-Newton and optical observations of three new polars found in the Sloan Digital Sky Survey. Simple modeling of the X-ray spectra, and consideration of the details of the X-ray and optical light curves corroborate the polar nature of these three systems and provide further insights into their accretion characteristics. During the XMM-Newton observation of SDSS J072910.68+365838.3, X-rays are undetected apart from a probable flare event, during which we find both the typical hard X-ray bremsstrahlung component and a very strong O VII (E=0.57 keV) line, but no evidence of a soft blackbody contribution. In SDSS J075240.45+362823.2 we identify an X-ray eclipse at the beginning of the observation, roughly in phase with the primary minimum of the optical broadband curve. The X-ray spectra require the presence of both hard and soft X-ray components, in a luminosity ratio consistent with that found in other recent XMM-Newton results on polars. SDSS J170053.30+400357.6 appears optically as a very typical polar; however, its large-amplitude optical modulation is 180° out of phase with the variation in our short X-ray light curve.

Some of the results presented here were obtained with the MMT Observatory, a facility operated jointly by The University of Arizona and the Smithsonian Institution.

Based on observations obtained with the Sloan Digital Sky Survey and the Apache Point Observatory (APO) 3.5 m telescope, which are owned and operated by the Astrophysical Research Consortium (ARC).