FUV and X-ray irradiated protoplanetary disks: a grid of models II - Gas diagnostic line emission. (arXiv:1209.0591v1 [astro-ph.SR])

FUV and X-ray irradiated protoplanetary disks: a grid of models II - Gas diagnostic line emission. (arXiv:1209.0591v1 [astro-ph.SR]):
Most of the mass in protoplanetary disks is in the form of gas. The study of
the gas and its diagnostics is of fundamental importance in order to achieve a
detailed description of the thermal and chemical structure of the disk. The
radiation from the central star (from optical to X-ray wavelengths) and viscous
accretion are the main source of energy and dominates the disk physics and
chemistry in its early stages. This is the environment in which the first
phases of planet formation will proceed. We investigate how stellar and disk
parameters impact the fine-structure cooling lines [NeII], [ArII], [OI], [CII]
and H2O rotational lines in the disk. These lines are potentially powerful
diagnostics of the disk structure and their modelling permits a thorough
interpretation of the observations carried out with instrumental facilities
such as Spitzer and Herschel. Following Aresu et al. (2011), we computed a grid
of 240 disk models, in which the X-ray luminosity, UV-excess luminosity,
minimum dust grain size, dust size distribution power law and surface density
distribution power law, are systematically varied. We solve self-consistently
for the disk vertical hydrostatic structure in every model and apply detailed
line radiative transfer to calculate line fluxes and profiles for a series of
well known mid- and far-infrared cooling lines. The [OI] 63 micron line flux
increases with increasing FUV luminosity when Lx < 1e30 erg/s, and with
increasing X-ray luminosity when LX > 1e30 erg/s. [CII] 157 micron is mainly
driven by FUV luminosity via C+ production, X-rays affect the line flux to a
lesser extent. [NeII] 12.8 micron correlates with X-rays; the line profile
emitted from the disk atmosphere shows a double-peaked component, caused by
emission in the static disk atmosphere, next to a high velocity double-peaked
component, caused by emission in the very inner rim. (abridged)