Letters of Intent received in 2015

LoI 2017-286
The hydride toolbox

Topics

Molecular physics includes spin symmetries for astrophysically interesting hydrides
Hydrides in solid phase : physical processes and chemistry
Hydrides as probes of the diffuse ISM and of the CO-Dark gas
Hydrides as probes of the interaction of cosmic rays with matter, and relation with magnetic field structure
Hydrides in shocks, probing the stellar feedback
Hydrides as probes of PDRs and star forming regions, from local regions to the high redshift universe
Hydrides as probes of energetic processes XDRs, and AGN activity diagnostics (across redshift)
Hydrides as probes of the planet formation process

Rationale

Hydrides are among the first molecules detected in Astronomy, outside the solar system. Hydrides are defined as molecules, radicals and molecular ions containing only one ``heavy'' atom (\eg{} C, N, O, F, S, Cl, Ar, etc.) bound with hydrogen atoms. Such molecules are therefore relatively chemically simple. They lie at the root of interstellar chemistry, as hydrides are among the first species to form in initially atomic gas, together with molecular hydrogen and its associated ions. Despite this relative simplicity, building chemical models explaining the astronomical data on hydrides has required several decades. Several independent factors contributed to enhancing the difficulty. The relative scarcity of astronomical data due to the limited number of spectral lines accessible from the ground, the specific thermodynamic and chemical properties of hydrides of astrophysical interest, leading to slow formation processes for key species like CH^+ in average interstellar conditions, and the need for advanced modeling approaches combining fluid dynamics, gas phase and solid phase chemistries, and including radiative and chemical pumping. Thanks to the development of submillimeter astronomy, especially the Herschel satellite and the SOFIA airplane, the knowledge of astronomical hydrides has rapidly progressed. Advances in astronomical observations have been matched by similar progresses in theory and in laboratory data. Several hydrides are now accessible either from space or from the ground, including distant objects at high redshift. Hydrides are now detected in a wide range of environments, from the low density diffuse matter with mostly atomic hydrogen, up to the dense FUV illuminated interfaces of molecular gas and HII regions, to cold and dense prestellar cores, and to molecular shocks. Because water is the main ice constituent, hydrides are also important probes of the planet formation process, including the role of the snow line in the growth of planet embryos, and the emergence of planet atmospheres.
Hydride spectral lines bear interesting diagnostics of important properties of interstellar medium, be it local or at cosmological distances. This includes the molecular hydrogen content, the ionization rate due to cosmic rays, the dissipation rate of turbulence, the kinetic temperature, the magnetic field intensity, as well as the ice condensation and evaporation processes, and the evolutionary time scale of the matter through for instance the abundance ratio of spin symmetry states of H2 and hydrides like NH3.
The goal of this meeting is to bring together the molecular physics (gas phase and solid phase; theory and experiments) and astrophysical community interested in hydrides, and to benchmark the hydride diagnostic capabilities, to expand the validation domain from the local universe to distant systems.
We therefore expect that in addition to division H, scientist from divisions B (especially Laboratory astrophysics) F (disks and planet atmospheres) , G (protostars evolution ; evolved star) and J (high redshift galaxies) will be interested by this meeting. We plan to invite scientists from these 5 divisions to participate to the SOC.