Photospheric emission as the dominant radiation mechanism in
  long-duration gamma-ray bursts
  We present the results of a set of numerical simulations of long-duration
gamma-ray burst jets associated with massive, compact stellar progenitors. The
simulations extend to large radii and allow us to locate the region in which
the peak frequency of the advected radiation is set before the radiation is
released at the photosphere. Light curves and spectra are calculated for
different viewing angles as well as different progenitor structures and jet
properties. We find that the radiation released at the photosphere of
matter-dominated jets is able to reproduce the observed Amati and
energy-Lorentz factor correlations. Our simulations also predict a correlation
between the burst energy and the radiative efficiency of the prompt phase,
consistent with observations.
