The Galactic Centre hosts a puzzling stellar population in its inner
few parsecs, with a high abundance of surprisingly young, relatively
massive stars bound within the deep potential well of the
central supermassive black hole, Sagittarius A*. Previous
studies suggest that the population of objects emitting soft X-rays
(less than 10 kiloelectronvolts) within the surrounding hundreds
of parsecs, as well as the population responsible for unresolved
X-ray emission extending along the Galactic plane, is dominated
by accreting white dwarf systems. Observations of diffuse hard X-ray
(more than 10 kiloelectronvolts) emission in the inner 10
parsecs, however, have been hampered by the limited spatial resolution
of previous instruments. Here we report the presence of a
distinct hard-X-ray component within the central 4 X 8 parsecs, as
revealed by subarcminute-resolution images in the 20β40 kiloelectronvolt
range. This emission is more sharply peaked towards the
Galactic Centre than is the surface brightness of the soft-X-ray
population. This could indicate a significantly more massive
population of accreting white dwarfs, large populations of lowmass
X-ray binaries or millisecond pulsars, or particle outflows
interacting with the surrounding radiation field, dense molecular
material or magnetic fields. However, all these interpretations pose
significant challenges to our understanding of stellar evolution,
binary formation, and cosmic-ray production in the Galactic
Centre