Have we found the counterpart signal of the Fermi bubbles at the cosmic-ray positrons?

The inner galaxy has hosted cosmic-ray burst events including those responsible for the gamma-ray extit{Fermi} bubbles and the extit{eROSITA} bubbles in X-rays. In this work, we study the extit{AMS-02} positron fraction and find three features around 12, 21 and 48 GeV of which the lowest energy has a 1.4 to 4.9-$sigma$ significance, depending on astrophysical background assumptions. Using background simulations that explain the cosmic-ray positron fraction, positron flux and electron plus positron flux, by primary, secondary cosmic rays and cosmic rays from local pulsars, we test these spectral features as originating from electron/positron burst events from the inner galaxy. We find the 12 GeV feature, to be explained by an event of age $ au simeq 3 - 10$ Myr; in agreement with the proposed age of the extit{Fermi} bubbles. Furthermore, the energy in cosmic-ray electrons and positrons propagating along the galactic disk and not within the extit{Fermi} bubbles volume, is estimated to be $10^{51.5}-10^{57.5}$ ergs, or $O(10^{-4}) -O(1)$ the cosmic-ray energy causing the extit{Fermi} bubbles. We advocate that these positron fraction features, are the counterpart signals of the extit{Fermi} bubbles, or of substructures in them, or of the extit{eROSITA} bubbles.