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A great portion of the cataclysmic variable population, between 40% and 70%,is predicted to be made up of period-bouncers, systems with degenerate donorsthat have evolved past the period minimum. However, due to their intrinsicfaintness, only a few of these systems have been observed and confidentlyidentified so far. We have searched for X-ray emission as a proof of accretionin order to confirm period-bounce cataclysmic variables. In a dedicatedXMM-Newton observation of the period-bounce candidate SDSS J151415.65+074446.5we discovered X-ray modulation at the binary orbital period confirming it as anaccreting system. The X-ray light curve and the X-ray spectrum displaycharacteristics of magnetic Polar-type systems allowing for the first time thedetermination of the X-ray luminosity and mass accretion rate for this system.Catalog data from eROSITA on the SRG satellite for V379 Vir and SDSSJ125044.42+154957.4 allowed a first look into the X-ray behavior ofperiod-bounce candidates with this new all-sky instrument. From the eROSITAmeasurements the X-ray luminosity and mass accretion rate were determined forthe first time for SDSS J125044.42+154957.4, and the earlier result for V379Vir from XMM-Newton was confirmed. All three cataclysmic variables with amagnetic white dwarf and very low-mass donor studied in this work presentevidence for X-ray emission at a similar level of $L_{\rm x}\,{\rm [erg/s]}\approx 10^{29}$, which, together with the detection of X-ray orbitalmodulation in two of them, V379 Vir and SDSS J151415.65+074446.5, unambiguouslyproves the presence of accretion in these systems. The detection of theseperiod-bouncers at faint X-ray luminosity levels with the all-sky X-ray surveyeROSITA offers new prospects for the identification of additionalperiod-bouncers, providing impetus for theoretical studies of binary evolution.

New X-ray detections of magnetic period-bounce cataclysmic variables from XMM-Newton and SRG/eROSITA