DIG_HR

This grid is only available in the 3MdB database (Cloudy c13 models).

The Diffuse Ionized Gas (DIG) was detected through its optical line emission outside the classical HII regions and turns out to be a major component of the interstellar medium in galaxies. An electron density ~0.1 cm^-3 and temperature ~10^4 K are the physical conditions that characterize the DIG. The main ionizing and heating sources of the DIG, were unknown for several decades. Flores-Fajardo (2011) have shown that photoionization models taking into account photons emitted by OB stars and leaking out of HII regions located in the galactic thin disk combined to photons coming from the expected population of Hot LoMass Evolved Stars (HOLMES) are able to reproduce the emission-line features observed in edge-on galaxies...

We developed a grid of plane-parallel, ionization-bounded models included in 3MdB under the reference "DIG\_HR'' in which we combine two ionizations sources: one coming from the unabsorbed OB stars and one coming from the HOLMES. Unlike of the original grid, the one included in 3MdB is a real high resolution grid in the sense that no interpolation between models is required, meaning that each point of the grid is an a independent and complete CLOUDY model.

All the models are ionization-bounded, as described in Flores-Fajardo (2011) : http://adsabs.harvard.edu/abs/2011MNRAS.415.2182F

In "DIG_HR'', the SED (Spectral Energy Distribution) representing the OB stars is fixed and was developed with the evolutionary stellar population synthesis code STARBURST99 v 7.0.1 Leitherer (1999), while the SED representing the HOLMES is fixed too and was developed with the evolutionary spectral synthesis code PEGASE.2 (Fioc, 1997), both with the detailed characteristics described in Flores-Fajardo (2011) determined for the galaxy NGC891. In addition, each model is defined by the value of the OB surface flux Phi_OB, the ionization parameter U and the chemical composition of the gas. The surface flux log Phi_OB are going from 3.5 to 7.5 with a step of 0.25. The ionization parameter is defined as U = Phi_total / n_e c where Phi_total = Phi_OB + Phi_HOLMES, n_e is the electron density and c is the speed of light. The value of Phi_HOLMES = 8.4 x 10^4 photons/s/cm^2 is the same for all the models in this grid and once Phi_OB is set, the value of U defining the models are varied by changing the electron density n_e. The values of logU are going from -4.0 to -3.0 with a step of 0.1. Finally, the abundances of the heavy elements (except N) relative to O are fixed to their solar values as implemented in CLOUDY. Mg, Si and Fe are depleted by 1 dex and log O/H is going from -4.3 to 2.7 while log N/O varies from -1.4 to -0.2, both with a step of 0.1 dex. The combination of all these parameters (see Table below) produces 41327 models computed and included in 3MdB.

Format of the "com" fields: