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We have modelled the high-energy astrophysics of the inner 200 pc of theGalaxy with a view to explaining the diffuse, broad-band (radio continuum toTeV gamma-ray), non-thermal signal detected from this region. Our modellingpins down the ISM parameters for the environment wherein cosmic ray (CR)electrons and ions reside in the Galactic centre (GC). We find that themagnetic field in this region is 100-300 microG, the gas density < 60 cm^-3,and that a powerful (> 200 km/s) 'super'-wind acts to remove > 95% of thecosmic rays accelerated in the region before they have time to lose theirenergy in situ. The ~ 10^39 erg/s carried away by the GC cosmic ray protons isprecisely enough to energise the ~GeV gamma-ray emission from the Fermi'bubbles' recently found to extend north and south of the GC out to distancesof ~10 kpc, provided that the bubbles constitute thick targets to the GCprotons and that the situation has reached steady state. In such a situation of'saturation' the hard, uniform spectrum of the bubbles are explained andsecondary electron synchrotron explains the non-thermal microwave emissionfound in WMAP data mirroring the bubbles. Given the very low density of thebubble plasma (<0.01 cm^-3), the pp loss time in the Bubbles is > 5 Gyr. Ourscenario thus has the startling implication that a GC source of nonthermalparticles of time-averaged power 10^39 erg/s has persisted since the youth ofthe Galaxy.

Galactic centre star formation writ large in gamma-rays