J/ApJ/812/146 Line-of-sight velocities from bar simulations (Molloy+, 2015)
Resonant orbits and the high velocity peaks toward the bulge.
Molloy M., Smith M.C., Evans N.W., Shen J.
<Astrophys. J., 812, 146 (2015)>
=2015ApJ...812..146M 2015ApJ...812..146M (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Models
Keywords: galaxies: bulges; galaxies: evolution;
galaxies: kinematics and dynamics; Galaxy: bulge; Galaxy: evolution;
Galaxy: kinematics and dynamics
Abstract:
We extract the resonant orbits from an N-body bar that is a good
representation of the Milky Way, using the method recently introduced
by Molloy et al. (2015ApJ...804...80M 2015ApJ...804...80M). By decomposing the bar into
its constituent orbit families, we show that they are intimately
connected to the boxy-peanut shape of the density. We highlight the
imprint due solely to resonant orbits on the kinematic landscape
toward the Galactic center. The resonant orbits are shown to have
distinct kinematic features and may be used to explain the cold
velocity peak seen in the Apache Point Observatory Galactic Evolution
Experiment commissioning data. We show that high velocity peaks are a
natural consequence of the motions of stars in the 2:1 orbit family
and that stars on other higher order resonances can contribute to the
peaks. The locations of the peaks vary with bar angle and, with the
tacit assumption that the observed peaks are due to the 2:1 family, we
find that the locations of the high velocity peaks correspond to bar
angles in the range 10°≲θbar≲25°. However, some
important questions about the nature of the peaks remain, such as
their apparent absence in other surveys of the Bulge and the
deviations from symmetry between equivalent fields in the north and
south. We show that the absence of a peak in surveys at higher
latitudes is likely due to the combination of a less prominent peak
and a lower number density of bar supporting orbits at these
latitudes.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 24 32 *Line-of-sight velocity distributions for each of
the APOGEE commissioning fields
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Note on table1.dat: Apache Point Observatory Galactic Evolution Experiment
(APOGEE; SDSS-III) commissioning fields of Nidever et al. (2012ApJ...755L..25N 2012ApJ...755L..25N)
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See also:
J/ApJS/216/12 : OGLE-III microlensing events (Wyrzykowski+, 2015)
J/A+A/563/A15 : Metallicity and kinematics in Galactic bar (Babusiaux+, 2014)
J/A+A/562/A66 : GIRAFFE Inner Bulge Survey (GIBS). I. (Zoccali+, 2014)
J/ApJ/721/L28 : Red clump stars in Galactic Bulge from OGLE-III (Nataf+, 2010)
J/ApJ/691/1387 : Spectroscopy of the Galactic bar. I. (Rangwala+, 2009)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 4 F4.1 deg GLON [4/14] Galactic longitude
6- 9 F4.1 deg GLAT [-4.3/2] Galactic latitude
11- 12 I2 deg theta [10/25] Viewing angle of the bar (θbar)
14- 17 F4.1 km/s Allpk [41/87.1] Peak of fit to all particles (1)
19- 24 F6.2 km/s 21pk [128/253.1] Maximum peak of three Gaussian fit (2)
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Note (1): This is the peak value of the Chi-squared fit of a single component
Gaussian to all simulation particles in the field.
Note (2): This is the maximum peak of the 3-component Gaussian mixture model
for only the 2:1 resonant orbits in the field.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 05-Feb-2016