Two new magnetic cataclysmic variables discovered in the 3XMM catalogue

Abstract

X-ray catalogues provide a wealth of information on many source types, ranging from compact objects to galaxies, clusters of galaxies, stars, and even planets. Thanks to the huge volume of X-ray sources provided in the 3XMM catalogue, along with many source specific products, many new examples from rare classes of sources can be identified. Through visualising spectra and lightcurves from about 80 observations included in the incremental part of the 3XMM catalogue, 3XMM-DR5, as part of the quality control of the catalogue, we identified two new X-ray sources, 3XMM J183333.1+225136 and 3XMM J184916.1+652943, that were highly variable. This work aims to investigate their nature. Through simple model fitting of the X-ray spectra and analysis of the X-ray lightcurves of 3XMM J183333.1+225136 and 3XMM J184916.1+652943, along with complementary photometry from the XMM-Newton Optical Monitor, Pan-Starrs and the Stella/WiFSIP and Large Binocular Telescope (LBT) spectra, we suggest that the two sources might be magnetic cataclysmic variables (CVs) of the polar type and we determine some of their properties. Both CVs have very hard spectra, showing no soft excess. They are both situated in the local neighbourhood, located within $\sim$1 kpc. 3XMM J183333.1+225136 has an orbital period of 2.15 hours. It shows features in the lightcurve that may be a total eclipse of the white dwarf. 3XMM J184916.1+652943 has an orbital period of 1.6 hours. Given that only a small sky area was searched to identify these CVs, future sensitive all sky surveys such as the eROSITA project should be very successful at uncovering large numbers of such sources.

8 pages, 11 figures, A&A, in press

References in corpus (11)

• Second ROSAT all-sky survey (2RXS) source catalogue
• The XMM-Newton Serendipitous Survey. V. The Second XMM-Newton Serendipitous Source Catalogue
• The Donor Stars of Cataclysmic Variables
• X-ray Emissions from Accreting White Dwarfs: a Review
• 20-100 keV properties of cataclysmic variables detected in the INTEGRAL/IBIS survey
• Broad-band characteristics of seven new hard X-ray selected cataclysmic variables
• The serendipituous discovery of a short-period eclipsing polar in 2XMMp
• XMM-Newton observations of the Galactic globular clusters NGC 2808 and NGC 4372
• 2XMMi J225036.9+573154 - a new eclipsing AM Her binary discovered using XMM-Newton
• Characterizing Three Candidate Magnetic CVs from SDSS: XMM-Newton and Optical Follow-up Observations
• Current Status of the Facility Instrumentation Suite at The Large Binocular Telescope Observatory

Cited by in corpus (6)

• On the space density of X-ray selected cataclysmic variables
• Compact white-dwarf binaries in the combined SRG/eROSITA/SDSS eFEDS survey
• Identification of 3XMM J000511.8+634018 as a new polar at P(orb)=133.5 min -- is it inside or outside the period gap?
• Serendipitous discovery of the magnetic cataclysmic variable SRGE J075818-612027
• Discovery of the magnetic cataclysmic variable XMM J152737.4-205305.9 with a deep eclipse-like feature
• PTF1J2224+17: a short-period, high-field polar