Further evidence that the Milky Way bar has undergone a buckling phase. (arXiv:1911.04716v1 [astro-ph.GA])
<a href="http://arxiv.org/find/astro-ph/1/au:+Paterson_D/0/1/0/all/0/1">Dylan Paterson</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Coleman_B/0/1/0/all/0/1">Brendan Coleman</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gordon_C/0/1/0/all/0/1">Chris Gordon</a>
Studies of the red clump giant population in the inner Milky Way suggest the
Galactic bulge/bar has a boxy/peanut/X-shaped structure as predicted by its
formation via a disc buckling instability. We used a new non-parametric method
of estimating the Galactic bulge morphology that is based on maximum entropy
methods. With our maximum entropy deconvolution method we extracted the
three-dimensional distribution of the red giant stars in the bulge from deep
photometric catalogues of the VISTA Variables in the Via Lactea (VVV) survey.
Our high-resolution reconstruction confirms the well known boxy/peanut/X-shaped
structure of the bulge and also shows spurs which extend to around three kpc in
front of and behind the bulge. One of those spurs is above the major axis of
the bulge and the other is below the major axis. This is a key diagnostic of a
post-buckling phase of the bulge. Additionally, at distances over 500 pc above
or below the Galactic plane we find that the X-arms are on the same side of the
bulge major axis as their corresponding spurs. Closer to the Galactic plane,
the X-arms are on opposite sides of the major axis of the bulge. This implies a
twisting in the X-shape of the bulge.
Studies of the red clump giant population in the inner Milky Way suggest the
Galactic bulge/bar has a boxy/peanut/X-shaped structure as predicted by its
formation via a disc buckling instability. We used a new non-parametric method
of estimating the Galactic bulge morphology that is based on maximum entropy
methods. With our maximum entropy deconvolution method we extracted the
three-dimensional distribution of the red giant stars in the bulge from deep
photometric catalogues of the VISTA Variables in the Via Lactea (VVV) survey.
Our high-resolution reconstruction confirms the well known boxy/peanut/X-shaped
structure of the bulge and also shows spurs which extend to around three kpc in
front of and behind the bulge. One of those spurs is above the major axis of
the bulge and the other is below the major axis. This is a key diagnostic of a
post-buckling phase of the bulge. Additionally, at distances over 500 pc above
or below the Galactic plane we find that the X-arms are on the same side of the
bulge major axis as their corresponding spurs. Closer to the Galactic plane,
the X-arms are on opposite sides of the major axis of the bulge. This implies a
twisting in the X-shape of the bulge.
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