What is the reason for the lack of cool evolved stars near the center of the Galaxy?

Abstract: The observed deficit of bright late-type giants in the central parsec of the Milky Way remains an open problem. We investigate whether repeated passages of red giants (RGs) through a past jet from Sgr$~$A$<sup>*$ can modify their envelopes and apparent spectral types. Three-dimensional hydrodynamical simulations follow a $1\,M_\odot$, $100\,R_\odot$ RG through up to ten jet crossings at $10<sup>{-3}\,\text{pc}$, using jet kinetic luminosities of $10<sup>{42}$, $10<sup>{44}$, and $10<sup>{48}\,\text{erg}\,\text{s}<sup>{-1}$. Each passage produces shocks, envelope ablation, and an asymmetric downstream tail. For jet luminosities up to $10<sup>{44}\,\text{erg}\,\text{s}<sup>{-1}$, the cumulative ablated mass evolves approximately as $ΔM\propto t<sup>{1/2}$ and reaches about $10<sup>{-4}\,M_\odot$ over a $10<sup>5\,\text{yr}$ active phase. Repeated heating also raises the surface temperature from about $3600$ to $8500\,\text{K}$ during the first ten passages, potentially making an M-type giant appear as an A-type source. Jet feedback may therefore contribute to the apparent depletion of cool giants and the excess of hot stars in galactic nuclei (GN).