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Metal enrichment in the Lyman-alpha forest
Sara Ellison (IoA)
The Lyman Alpha forest was first observed in the late 1960s as a plethora
of absorption lines seen blueward of Lyman Alpha emission in high redshift
QSOs. Our current understanding of the Lya forest is that it is the
intergalactic medium (IGM) with HI absorption seen in structures such as
sheets and filaments as predicted by gas hydrodynamical simulations.
First thought to contain pristine material unenriched by previous episodes
of star formation, it is now well established that a large fraction of
high column density Lya clouds have associated metal lines, most notabley
CIV. By studying the CIV/HI ratio of the weaker absorption systems, we
may be able to distinguish possible mechanisms for this IGM enrichment and
determine whether the metals were produced locally or whether the entire
IGM was seeded with metals by a global epoch of Pop III star formation at
very high redshifts.
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