  While Gamma Ray Bursts (GRBs) have the potential to shed light on the
astrophysics of jets, compact objects, and cosmology, a major set back in their
use as probes of these phenomena stems from our incomplete knowledge
surrounding their prompt emission. There are numerous models that can account
for various observations of GRBs in the gamma-ray and X-ray energy ranges due
to the flexibility in the number of parameters that can be tuned to increase
agreement with data. Furthermore, these models lack predictive power that can
test future spectropolarimetric observations of GRBs across the electromagnetic
spectrum. In this work, we use the MCRaT radiative transfer code to calculate
the X-ray spectropolarimetric signatures expected from the photospheric model
for two unique hydrodynamic simulations of long GRBs. We make time-resolved and
time-integrated comparisons between the X-ray and gamma-ray mock observations,
shedding light on the information that can be obtained from X-ray prompt
emission signatures. Our results show that the $T_{90}$ derived from the X-ray
lightcurve is the best diagnostic for the time that the central engine is
active. We also find that our simulations reproduce the observed
characteristics of the Einstein Probe detected GRB240315C. Based on our
simulations, we are also able to make predictions for future X-ray
spectropolarimetric measurements. Our results show the importance of conducting
global radiative transfer calculations of GRB jets to better contextualize the
prompt emission observations and constrain the mechanisms that produce the
prompt emission.
