Charge exchange in the ultraviolet: implication for interacting clouds
  in the core of NGC 1275
  Charge exchange emission is known to provide a key diagnostic to the
interface between hot and cold matter in many astrophysical environments. Most
of the recent charge exchange studies focus on its emission in the X-ray band,
but few on the UV part, although the latter can also provide a powerful probe
of the charge exchange process. An atomic calculation, as well as an
application to observed data, are presented to explore and describe the
potential use of the UV data for the study of cosmic charge exchange. Using the
newest charge exchange model in the SPEX code v3.03, we re-analyze an archival
Hubble STIS data of the central region of NGC 1275. The NGC 1275 spectrum shows
hints for three possible weak lines at about 1223.6~{\AA}, 1242.4~{\AA}, and
1244.0~{\AA}, each with a significance of about $2-3\sigma$. The putative
features are best explained by charge exchange between highly ionized hydrogen,
neon, and sulfur with neutral matter. The wavelengths of the charge exchange
lines are found robustly with uncertainties $\leq 0.3$~{\AA}. The possible
charge exchange emission shows a line-of-sight velocity offset of about $-3400$
km s$^{-1}$ with respect to the NGC 1275 nucleus, which resembles one of the
Ly$\alpha$ absorbers reported in Baum et al. (2005). This indicates that the
charge exchange lines might be emitted as the same position of the absorber,
which could be ascribed to outflowing gas from the nucleus.
