| Description |
We propose to use the The Galactic center (GC) a local extragalactic laboratory tounderstand the chemistry and the heating mechanisms in nearby galactic nuclei. Thecentral 30 pc region around the black hole, Sgr A*, contains all the different typeof activity found in extragalactic nuclei, namely, massive stellar clusterscreating large photodissociation regions (PDR), shocks, molecular clouds irradiatedby strong X-rays (XDRs), and the site of Cosmic Rays (CRs) acceleration as shown byHESS. We plan to map this region with SPIRE in the high spectral resolution mode and with HIFI in selected molecular ions H$_3$O$^+$, OH$^+$, and H$_2$O$^+$ claimed totrace XDRs and/or CRs. This unique data set will provide the possibility to understandthe origin of the large column densities of this hydrides found in galactic nucleiwith different type of activity and the role of the PDR-XDR-CR chemistries in theirformation. The SPIRE data cubes will have a huge legacy value providing the full FIRinventory of the atomic and molecular gas across the central 50 pc of the Galaxy. Westress that only the combination of the high spectral resolution of HIFI and thespatial distribution provided the proposed mapping will have the possibility todistinguish which of the different components of the molecular gas along the line ofsight correspond to the ones associated with XDRs PDRs and eventually CRsacceleration sites. |
