An Analysis of HCN Observations of The Galactic Centre's Circumnuclear Disk

TL;DR

This study uses Large Velocity Gradient modeling of HCN observations to estimate the density of the Galactic Centre's Circumnuclear Disk, revealing it is less dense than needed to resist tidal forces from the central black hole.

Contribution

It provides the first detailed density estimates of CND clumps using HCN line modeling, highlighting their vulnerability to tidal shear.

Findings

Hydrogen density of CND clumps is about 10^6 cm^-3.

CND clumps are insufficiently dense to withstand tidal shear.

The analysis offers new insights into the physical conditions of the Galactic Centre.

Abstract

The Circumnuclear Disk (CND) is a torus of dust and moleular gas rotating about the galactic centre and extends from 1.6 to 7pc from the central massive black hole SgrA*. Large Velocity Gradient modelling of selected transitions of HCN rotational collisions with molecular hydrogen is used to infer Hydrogen density and HCN opacities. The analysis concludes that the predicted hydrogen number density of CND clumps is about 10^6 which is insufficiently dense to withstand the tidal shear forces generated by SgrA* and the stellar group in the cavity between the galactic centre and the CND.