An analysis of infrared emission spectra from the regions near the Galactic Center

TL;DR

This study models IR spectra near the Galactic Center, revealing shock velocities, magnetic fields, stellar temperatures, and dust properties, providing insights into the physical conditions and dust composition in this complex region.

Contribution

It offers a comprehensive coupled shock and photoionization model of IR spectra near the Galactic Center, incorporating dust and magnetic field effects for the first time.

Findings

Shock velocities between 65-80 km/s

Presence of silicate dust with Si depletion

Dust component at 100-200 K in the central Galaxy

Abstract

We present consistent modelling of line and continuum IR spectra in the region close to the Galactic center. The models account for the coupled effect of shocks and photoionization from an external source. The results show that the shock velocities range between 65 and 80 km/s, the pre-shock densities between 1 cm-3 in the ISM to 200 cm-3 in the filamentary structures. The pre-shock magnetic field increases from 5. 10^{-6} gauss in the surrounding ISM to ~8. 10^{-5} gauss in the Arched Filaments. The stellar temperatures are ~38000 K in the Quintuplet cluster and ~27000 K in the Arches Cluster. The ionization parameter is relatively low (<0.01) with the highest values near the clusters, reaching a maximum >0.01 near the Arches Cluster. Depletion from the gaseous phase of Si is found throughout the whole observed region, indicating the presence of silicate dust. Grains including iron, are concentrated throughout the Arched Filaments. The modelling of the continuum SED in the IR range, indicates that a component of dust at temperatures of ~100-200 K is present in the central region of the Galaxy. Radio emission appears to be thermal bremsstrahlung in the E2-W1 filaments crossing strip, however a synchrotron component is not excluded. More data are necessary to resolve this questions.