Shock fronts in the long GRB031203 host galaxy
  The detailed modelling of the spectra observed from the long GRB031203 host
galaxy at different epochs during the 2003-2009 years is presented. The line
profiles show FWHM of about 100 km/s. A broad line profile with FWHM < 400 km/s
appears in the line sockets from the 2009 observations. We suggest that the
narrow lines show the velocity of star-burst (SB) debris, while the broad ones
are due to the wind from SB stars. The spectra are emitted from the gas
downstream of different shock fronts which are at work on the edges of the
emitting clouds. A head-on-back shock appears when the wind from the SB stars
reaches the internal edge of the SB debris moving outwards. A head-on shock is
created by collision of the debris with the ISM clouds.Line ratios in both
cases are calculated by the coupled effect of shock and photoionization from
the SB. The models selected by fitting the calculated to the observed line
ratios show that the ionization parameters, the shock velocities and the gas
pre-shock densities slowly decrease with time.Oxygen metallicities
(12+log(O/H)=8.3-8.48) are lower than solar (8.82) by a factor <3 and nitrogen
metallicities are lower than solar (12+log(N/H)=8.0) by factors of 3-5.
