Abstract
In hierarchical cosmological models, galaxies grow in mass through the
continual accretion of smaller ones. The tidal disruption of these
systems is expected to result in loosely bound stars surrounding the
galaxy, at distances that reach 10-100 times the radius of the central
disk. The number, luminosity and morphology of the relics of this
process provide significant clues to galaxy formation history, but
obtaining a comprehensive survey of these components is difficult
because of their intrinsic faintness and vast extent. Here we report a
panoramic survey of the Andromeda galaxy (M31). We detect stars and
coherent structures that are almost certainly remnants of dwarf galaxies
destroyed by the tidal field of M31. An improved census of their
surviving counterparts implies that three-quarters of M31's satellites
brighter than Mv = -6 await discovery. The brightest
companion, Triangulum (M33), is surrounded by a stellar structure that
provides persuasive evidence for a recent encounter with M31. This
panorama of galaxy structure directly confirms the basic tenets of the
hierarchical galaxy formation model and reveals the shared history of
M31 and M33 in the unceasing build-up of galaxies.
Original language | English |
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Pages (from-to) | 66-69 |
Journal | Nature |
Volume | 461 |
DOIs | |
Publication status | Published - 3 Sept 2009 |