X-ray extinction from interstellar dust: Prospects of observing carbon,
  sulfur and other trace elements
  We present a study on the prospects of observing carbon, sulfur, and other
lower abundance elements (namely Al, Ca, Ti and Ni) present in the interstellar
medium using future X-ray instruments. We focus in particular on the detection
and characterization of interstellar dust along the lines of sight. We compare
the simulated data with different sets of dust aggregates, either obtained from
past literature or measured by us using the SOLEIL-LUCIA synchrotron beamline.
Extinction by interstellar grains induces modulations of a given photolelectric
edge, which can be in principle traced back to the chemistry of the absorbing
grains. We simulated data of instruments with characteristics of resolution and
sensitivity of the current Athena, XRISM and Arcus concepts. In the relatively
near future, the depletion and abundances of the elements under study will be
determined with confidence. In the case of carbon and sulfur, the
characterization of the chemistry of the absorbing dust will be also
determined, depending on the dominant compound. For aluminum and calcium,
despite the large depletion in the interstellar medium and the prominent dust
absorption, in many cases the edge feature may not be changing significantly
with the change of chemistry in the Al$^-$ or Ca$^-$ bearing compounds. The
exinction signature of large grains may be detected and modeled, allowing a
test on different grain size distributions for these elements. The low cosmic
abundance of Ti and Ni will not allow us a detailed study of the edge features.
