Atomic Data Needs for Understanding X-ray Astrophysical Plasmas

High-resolution X-ray data from current satellites expose the need for high-quality atomic data of all stripes: wavelengths, collisional/radiative rates, and absorption cross sections. Astro-H, to be launched in 2015, will increase the available effective area for high-resolution at some energies by orders of magnitude, bringing the issue into sharp relief. There have been a number of recent successes of both theoretical calculations and laboratory measurements, as well as many remaining atomic data needs which hinder scientific progress (e.g Fe XVII line ratios). These include, amongst other issues, accurate wavelength measurements in the soft X-ray band, well-calibrated diagnostic ratios of select lines, and high-resolution absorption cross sections for abundant ions. Finally, astrophysical charge exchange, a newly identified contribution to soft X-ray emission, will be discussed. This emission arises due to the interaction of highly charged ions with neutral atoms, forming a diffuse background due to solar wind ions interacting in the heliosphere and possibly also arising in more distant environments.