  We take hydrodynamic initial conditions in relativistic heavy ion collisions
from the Color Glass Condensate (CGC) picture through the kT factorization
formula. Gluon distributions produced from the CGC are found to provide good
initial conditions for the hydrodynamic simulations in Au + Au collisions at
Relativistic Heavy Ion Collider (RHIC) energies. We reproduce the centrality,
rapidity, and energy dependences of multiplicity within this approach. We also
investigate the energy loss of high pT partons in the dense thermalized medium
created from colliding two CGC's. We find that our results on the centrality
dependence of nuclear modification factors for pions and back-to-back
correlation for charged hadrons at midrapidity are consistent with the RHIC
data up to semicentral events. Whereas, our approach in which jets are
calculated from perturbative QCD 2->2 processes predicts less suppression at
forward rapidity region compared to the BRAHMS data in Au+Au collisions at
RHIC.
