Detalles de publicación

PP 018026

Signatures of the Galactic bar on stellar kinematics unveiled by APOGEE

Pedro Alonso Palicio (1,2), Inma Martinez-Valpuesta (1,2), Carlos Allende Prieto (1,2), Claudio Dalla Vecchia (1,2), Olga Zamora (1,2), Gail Zasowski (3,4), J. G. Fernandez-Trincado (5,6), Karen L. Masters (7,8), D. A. García-Hernández (1,2), Alexandre Roman-Lopes (9)
(1)IAC, (2)ULL, (3)Space Telescope Science Institute, (4)Department of Physics and Astronomy, University of Utah, (5) Departamento de Astronomía, Universidad de Concepción, (6) Institut Utinam, CNRS UMR6213, Univ. Bourgogne Franche-Comté, OSU THETA , Observatoire de Besançon, (7)Institute of Cosmology and Gravitation, University of Portsmouth, (8)Haverford College, Department of Physics and Astronomy, (9)Departamento de Fsica, Facultad de Ciencias, Universidad de La Serena
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 make use of two different numerical simulations --one that has developed a bar and one that remains nearly axisymmetric-- to compare them with observations in the latest APOGEE 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=0º 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.

 
Aceptado para publicación en MNRAS | Enviado el 2018-03-06 | Proyecto P/301502, P/301008