Xmm-newton Observations of the Extremely Low Accretion Rate Polars Sdssj155331.12+551614.5 and Sdssj132411.57+032050.5

XMM-Newton observations of the Polar SDSSJ155331.12+551614.5 reveal that all the X-ray flux emerges at energies <2 keV. The best fit to the spectrum is with a thermal plasma with kT=0.8 keV plus a 20-90 eV black body, yielding a thermal X-ray luminosity of 8.0-9.5×10 ergs s. The low temperature and X-ray luminosity, together with the lack of variation of the X-ray flux during the observations, are all consistent with an extremely low accretion rate that puts the system in the bombardment regime of accretion, rather than accretion involving a standoff shock. It is likely that the observed X-rays originate from the M dwarf secondary star, thus providing a base activity level for late main sequence stars in close binaries. SDSSJ132411.57+032050.5 is detected by XMM-Newton at the faint EPIC-pn count rate of 0.0012±0.0003 giving an upper limit to the X-ray luminosity of ∼7×10 ergs s for a distance of 300 pc, which is also consistent with the above scenario. Subject headings: cataclysmic variables — stars:individual(SDSSJ155331.12+551614.5, SDSSJ132411.57+032050.5) — stars:magnetic fields — X-rays:stars