Low velocity shocks signatures of turbulent-dissipation in diffuse irradiated gas. (2013)
Keywords :
shock waves - astrochemistry - ISM molecules - ISM: kinematics and dynamics - ISM: abundances
Abstract:Large-scale motions in galaxies (supernovae explosions, galaxy collisions, galactic shear etc.) generate turbulence, which allows a fraction of the available kinetic energy to cascade down to small scales before it is dissipated. We establish and quantify the diagnostics of turbulence dissipation in mildly irradiated diffuse gas in the specific context of shock structures. We incorporated the basic physics of photon-dominated regions into a state-of-the-art steady-state shock code. We examined the chemical and
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Outputs from the grids of shock runs used in the paper.
* The first level of the directory tree decides the value for the
magnetic field (b=(B/Bo)/sqrt(nH), with Bo=1{mu}Gauss=10^-10^T):
b0.1/ for b=0.1
b1/ for b=1
* The second level decides the value for the density and the type of shock:
b0.1/J2g0/ has J-type shocks for nH=10^2^cm^-3^
b0.1/J3g0/ has J-type shocks for nH=10^3^cm^-3^
b0.1/J4g0/ has J-type shocks for nH=10^4^cm^-3^
b1/J2g0/ has J-type shocks for nH=10^2^cm^-3^
b1/J3g0/ has J-type shocks for nH=10^3^cm^-3^
b1/J4g0/ has J-type shocks for nH=10^4^cm^-3^
b1/C2g0/ has C-type shocks for nH=10^2^cm^-3^
b1/C3g0/ has C-type shocks for nH=10^3^cm^-3^
b1/C4g0/ has C-type shocks for nH=10^4^cm^-3^
* The third level contains :
- static/ the run to get the pre-shock thermal and chemical equilibrium
- steady/ the 'PDR' run from these pre-shock conditions.
- u<N>.o3/ each output from the run at u=N km/s.
- chemistry.in: the chemical network used
- species.in: the pre-shock chemical composition.
- input_mhd_run.u.template : the template with all physical parameters
used to sample the grid of velocities
* The fourth level contains for each run the following ascii files:
- cooling.out : local total emission from a number of species.
- energetics.out : various energy fluxes
- err_cool.out : a few error messages whichi have occurred during the run.
- excit.out : H2 excitation diagram throughout the shock
- fe_lines.out: zero (we discarded Fe emission)
- fe_pops.out: zero as well
- H2_lev.out: integrated column densities of each H2 level
- H2_line.out: integrated emission of 200 H2 lines
- info_mhd.out: an ascii file which describes the parameters used in
the run.
- intensity.out: integrated intensities of several atomic lines.
- jlb.out: a specific output file for J.L.B.
- mhd_coldens.out: column densities of all species along the shock
- mhd_phys.out: various physical quantities of interest along the shock
- mhd_speci.out: the chemical profile (abundances)
- populations.out: local populations of some atomic levels
- species.out: post-shock temperature and composition
Each ascii file has a self-explanatory first line which contains the
names of each quantities in the column below.
Pierre Lesaffre, pierre.lesaffre(at)lra.ens.fr
