  Long-duration gamma-ray bursts (LGRBs), thought to be produced during
core-collapse supernovae, may have a prominent neutron component in the outflow
material. If present, neutrons can change how photons scatter in the outflow by
reducing its opacity, thereby allowing the photons to decouple sooner than if
there were no neutrons present. Understanding the details of this process could
therefore allow us to probe the central engine of LGRBs, which is otherwise
hidden. Here, we present results of the photospheric emission from an LGRB jet,
using a combination of relativistic hydrodynamic simulations and radiative
transfer post-processing using the Monte Carlo Radiation Transfer (MCRaT) code.
We control the size of the neutron component in the jet material by varying the
equilibrium electron fraction $Y_{e}$, and we find that the presence of
neutrons in the GRB fireball affects the Band parameters $\alpha$ and $E_{0}$,
while the picture with the $\beta$ parameter is less clear. In particular, the
break energy $E_{0}$ is shifted to higher energies. Additionally, we find that
increasing the size of the neutron component also increases the total radiated
energy of the outflow across multiple viewing angles. Our results not only shed
light on LGRBs, but are also relevant to short-duration gamma-ray bursts
associated with binary neutron star mergers, due to the likelihood of a
prominent neutron component in such systems.
