Bibcode
Gerhard, Ortwin; Martinez-Valpuesta, Inma
Referencia bibliográfica
The Astrophysical Journal Letters, Volume 744, Issue 1, article id. L8, 5 pp. (2012).
Fecha de publicación:
1
2012
Número de citas
65
Número de citas referidas
54
Descripción
Recent data from the VVV survey have strengthened evidence for a
structural change in the Galactic bulge inward of |l| <= 4°. Here
we show with an N-body barred galaxy simulation that a boxy bulge formed
through the bar and buckling instabilities effortlessly matches measured
bulge longitude profiles for red clump stars. The same simulation
snapshot was earlier used to clarify the apparent boxy bulge—long
bar dichotomy, for the same orientation and scaling. The change in the
slope of the model longitude profiles in the inner few degrees is caused
by a transition from highly elongated to more nearly axisymmetric
isodensity contours in the inner boxy bulge. This transition is confined
to a few degrees from the Galactic plane; thus the change of slope is
predicted to disappear at higher Galactic latitudes. We also show that
the nuclear star count map derived from this simulation snapshot
displays a longitudinal asymmetry similar to that observed in the Two
Micron All Sky Survey (2MASS) data, but is less flattened to the
Galactic plane than the 2MASS map. These results support the
interpretation that the Galactic bulge originated from disk evolution
and question the evidence advanced from star count data for the
existence of a secondary nuclear bar in the Milky Way.