Forward-shock versus reverse-shock origin of Sgr A* emission

Determine whether the TeV emission associated with Sgr A* originates from cosmic rays accelerated at a forward shock on approximately 10-pc scales or at a reverse shock on sub-parsec scales followed by interactions in the central molecular zone.

Background

The paper primarily models Sgr A* as a point-like source whose TeV emission is produced by cosmic rays accelerated at a forward shock driven by an RIAF wind. It also considers a qualitative alternative in which fast sub-parsec outflows trace a reverse shock, with the accelerated cosmic rays later interacting with gas in the central molecular zone.

The available observations do not distinguish these acceleration sites. The authors therefore leave unresolved whether the forward-shock or reverse-shock interpretation is correct.

References

We note that this is only a qualitative alternative, which the present data cannot exclude. So far, both the forward-shock and reverse-shock interpretations remain possible.

— TeV Gamma Rays and Neutrinos from Winds Driven by Radiatively Inefficient Accretion Flows of Low-Luminosity Active Galactic Nuclei  (2608.30596 - Sakai et al., 31 Aug 2026) in Section 6, Application to Sgr A*