  We analyse the evolution of the properties of the low-redshift Intergalactic
Medium (IGM) using high-resolution hydrodynamic simulations that include a
detailed chemical evolution model. We focus on the effects that two different
forms of energy feedback, strong galactic winds driven by supernova explosion
and Active Galactic Nuclei (AGN) powered by gas accretion onto super-massive
black holes (BHs), have on the thermo- and chemo-dynamical properties of of the
low redshift IGM. We find that feedback associated to winds (W) and BHs leave
distinct signatures in both the chemical and thermal history of the baryons,
especially at redshift z<3 [..] We present results for the enrichment in terms
of mass and metallicity distributions for the WHIM phase, both as a function of
density and temperature. Finally, we compute the evolution of the relative
abundances between different heavy elements, namely Oxygen, Carbon and Iron.
While both C/O and O/Fe evolve differently at high redshifts for different
feedback models, their values are similar at z=0 [..]. The sensitivity of WHIM
properties on the implemented feedback scheme could be important both for
discriminating between different feedback physics and for detecting the WHIM
with future far-UV and X-ray telescopes.
