X-ray Spectroscopy of Accreting White Dwarfs

The advent of the grating spectrometers onboard Chandra and XMM-Newton opened up a new era in plasma diagnostics of compact binaries. High resolution spectroscopy using these spectrometers is of particular use in investigating accretion plasmas in cataclysmic variables (CVs) because they show a wealth of emission lines owing to their optically thin thermal nature. In this review, I present recent progress on density measurements of the plasma in magnetic CVs by means of He-like triplet and iron L lines, and the outcome of line velocity measurements in the dwarf nova SS Cygni in outburst, to demonstrate the potential power of high resolution spectroscopy to elucidate the geometry of the plasma. In the end, our expectations for the Soft X-ray Spectrometer onboard the forthcoming X-ray mission Astro-H are summarized.