Spectroscopy of Low Mass X-ray Binaries: New Insights Into Accretion

We propose to observe a sample of LMXBs, chosen for their Xray brightness, low column density, and diversity of accretion behavior. The high spectral resolution of the RGS, the broad energy range and substantial collecting powerof EPIC, and simultaneous optical monitoring with the OM will facilitate ourstudies. We will: investigate the physical conditions of the emitting gas using emission and recombination line diagnostics to determine temperatures,densities, elemental abundances, and ionization structure; study the behavior of emission features as a function of binary orbit; and test and improve models of Xray line emission developed by us over the past decade. We will gain insight on both the geometry of the accretion flow and on the evolutionary history of LMXBs. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]