J/A+A/669/A91 Gaia DR3 stars LMC/MW membership (Jimenez-Arranz+, 2023)
Kinematic analysis of the Large Magellanic Cloud using Gaia DR3
Jimenez-Arranz O., Romero-Gomez M., Luri X., McMillan P.J., Antoja T.,
Chemin L., Roca-Fabrega S., Masana E., Muros A.
<Astron. Astrophys. 669, A91 (2023)>
=2023A&A...669A..91J 2023A&A...669A..91J (SIMBAD/NED BibCode)
ADC_Keywords: Surveys ; Milky Way ; Magellanic Clouds ; Optical
Keywords: galaxies: kinematics and dynamics - Magellanic Clouds - astrometry
Abstract:
The high quality of the Gaia mission data is allowing to study the
internal kinematics of the Large Magellanic Cloud (LMC) in
unprecedented detail, providing insights on the non-axisymmetric
structure of its disc. Recent works by the Gaia Collaboration have
already made use of the excellent proper motions of Gaia DR2 and Gaia
EDR3 for a first such analysis, but were based on limited strategies
to distinguish the LMC stars from the Milky Way foreground that do not
use all the available information and could not use the third
component of the stellar motion, the line of sight velocity, that is
now available on Gaia DR3 for a significant number of stars.
Our aim is twofold: First, to define and validate an improved, more
efficient and adjustable selection strategy to distinguish the LMC
stars from the Milky Way foreground. Second, to check the possible
biases that assumed parameters or sample contamination from the Milky
Way can introduce in the analysis of the internal kinematics of the
LMC using Gaia data.
Our selection is based on a supervised Neural Network classifier using
as much as of the Gaia DR3 data as possible. Using this classifier we
select three samples of candidate LMC stars with different degrees of
completeness and purity; we validate these classification results
using different test samples and we compare them with the results from
the selection strategy used in the Gaia Collaboration papers, based
only on proper motions. We analyse the resulting velocity profiles and
maps for the different LMC samples, and we check how these results
change when using also the line-of-sight velocities, available for a
subset of stars.
We show that the contamination in the samples from Milky Way stars
affects basically the results for the outskirts of the LMC, and that
the analysis formalism used in absence of line-of-sight velocities
does not bias the results for the kinematics in the inner disc. For
the first time, we perform a kinematic analysis of the LMC using
samples with the full three dimensional velocity information from Gaia
DR3.
The detailed 2D and 3D kinematic analysis of the LMC internal dynamics
show that: the dynamics in the inner disc is mainly bar dominated; the
kinematics on the spiral arm over-density seem to be dominated by an
inward motion and a rotation faster than that of the disc in the piece
of the arm attached to the bar; contamination of MW stars seem to
dominate the outer parts of the disc and mainly affects old
evolutionary phases; uncertainties in the assumed disc morphological
parameters and line-of-sight velocity of the LMC can in some cases
have significant effects in the analysis.
Description:
Table of the LMC / MW classification probability of each object in the
Gaia DR3 base sample. A Probability value close to 1 (0) means a high
probability of being a LMC (MW) star.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
class.dat 47 18783272 LMC/MW classification
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See also:
I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)
Byte-by-byte Description of file: class.dat
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Bytes Format Units Label Explanations
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3- 21 I19 --- GaiaDR3 Gaia DR3 source_id
25- 47 E23.19 --- P [0/1] Probability of being a LMC/MW star (1)
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Note (1): A probability value close to 1 (0) means a high probability of being
a LMC (MW) star.
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Acknowledgements:
Oscar Jimenez-Arranz, ojimenez(at)icc.ub.edu, oscar.jimenez.1996(at)gmail.com,
Institut de Ciencies del Cosmos - Universitat de Barcelona (ICCUB), Spain
(End) Oscar Jimenez-Arranz [ICCUB, Spain], Patricia Vannier [CDS] 12-Oct-2022