Bibcode
Palicio, P. A.; Martinez-Valpuesta, I.; Allende Prieto, C.; Dalla Vecchia, C.; Zamora, O.; Zasowski, Gail; Fernandez-Trincado, J. G.; Masters, Karen L.; García-Hernández, D. A.; Roman-Lopes, Alexandre
Bibliographical reference
Monthly Notices of the Royal Astronomical Society, Volume 478, Issue 1, p.1231-1243
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7
2018
Citations
10
Refereed citations
7
Description
Bars are common galactic structures in the local universe that play an
important role in the secular evolution of galaxies, including the Milky
Way. In particular, the velocity distribution of individual stars in our
galaxy is useful to shed light on stellar dynamics, and provides
information complementary to that inferred from the integrated light of
external galaxies. However, since a wide variety of models reproduce the
distribution of velocity and the velocity dispersion observed in the
Milky Way, we look for signatures of the bar on higher order moments of
the line-of-sight velocity (V_{los}) distribution. We use two different
numerical simulations - one that has developed a bar and one that
remains nearly axisymmetric - to compare them with observations in the
latest Apache Point Observatory Galactic Evolution Experiment data
release (SDSS DR14). This comparison reveals three interesting
structures that support the notion that the Milky Way is a barred
galaxy. A high-skewness region found at positive longitudes constrains
the orientation angle of the bar, and is incompatible with the
orientation of the bar at ℓ = 0° proposed in previous studies.
We also analyse the V_{los} distributions in three regions, and
introduce the Hellinger distance to quantify the differences among them.
Our results show a strong non-Gaussian distribution both in the data and
in the barred model, confirming the qualitative conclusions drawn from
the velocity maps. In contrast to earlier work, we conclude it is
possible to infer the presence of the bar from the kurtosis
distribution.
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