Chandra and HST Snapshots of Fossil System Progenitors
  The search for the progenitors to today's fossil galaxy systems has been
restricted to N-body simulations until recently, where 12 fossil progenitors
were identified in the CASSOWARY catalog of strong lensing systems. All 12
systems lie in the predicted redshift range for finding fossils in mid
brightest group galaxy (BGG) assembly, and all show complex merging
environments at their centers. None of these progenitors had archival X-ray
data, and many were lacking high resolution optical data making precision
photometry extremely difficult. Here, we present Chandra and Hubble Space
Telescope (HST) snapshots of eight of these strong lensing fossil progenitors
at varying stages of evolution. We find that our lensing progenitors exhibit
higher than expected X-ray luminosities and temperatures consistent with
previously observed non-lensing fossil systems. More precise galaxy luminosity
functions are generated which strengthen past claims that progenitors are the
transition phase between non-fossils and fossils. We also find evidence
suggesting that the majority of differences between fossils and non-fossils lie
in their BGGs and that fossil systems may themselves be a phase of galaxy
system evolution and not a separate class of object.
