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The search for the progenitors to todays 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.
Fossil galaxy systems are classically thought to be the end result of galaxy group/cluster evolution, as galaxies experiencing dynamical friction sink to the center of the group potential and merge into a single, giant elliptical that dominates the r
The stellar initial mass function (IMF), which is often assumed to be universal across unresolved stellar populations, has recently been suggested to be bottom-heavy for massive ellipticals. In these galaxies, the prevalence of gravity-sensitive abso
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