092275

IPHAS J190132.77+145807.6 a very highly magnetised rapidly rotating massivewhite dwarf is an ideal target of an exploratory study to probe non-thermalX-ray emission processes and thereby to constrain fundamental physicalinteractions. Due to its extreme magnetic field and rotation conversion ofrotational energy to dipole radiation may be measurable at soft X-ray energies.Its mass close to the Chandrasekhar limit combined with its field strength makesit the most promising target to detect axion-induced keV emission. Even anon-detection would constrain the axions coupling parameters notably better.Given XMM-Newtons high sensitivity in the r^ant energy ranges a 70kspointing to this unusual white dwarf promises unique insights into so far scarcely observed phenomena. [truncated! Please see actual data for full text]