J/A+A/657/A54 Local Group Gaia eDR3 systemic motions (Battaglia+, 2022)
Gaia early DR3 systemic motions of Local Group dwarf galaxies and orbital
properties with a massive Large Magellanic Cloud.
Battaglia G., Taibi S., Thomas G.F., Fritz T.K.
<Astron. Astrophys. 657, A54 (2022)>
=2022A&A...657A..54B 2022A&A...657A..54B (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, nearby ; Proper motions ; Space velocities ; Optical
Keywords: methods: statistical - astrometry - galaxies: dwarf -
galaxies: evolution - galaxies: kinematics and dynamics - Local Group
Abstract:
We perform a comprehensive determination of the systemic proper
motions of 74 dwarf galaxies and dwarf galaxy candidates in the Local
Group based on Gaia early data release 3. The outputs of the analysis
for each galaxy, including probabilities of membership, will be made
publicly available. The analysis is augmented by a determination of
the orbital properties of galaxies within 500kpc.
We adopt a flexible Bayesian methodology presented in the literature,
which takes into account the location of the stars on the sky, on the
colour-magnitude diagram, and on the proper motion plane. We applied
some modifications, in particular to the way the colour-magnitude
diagram and spectroscopic information are factored in, for example, by
including stars in several evolution phases. The bulk motions were
integrated in three gravitational potentials: two where the Milky Way
was treated in isolation and has a mass 0.9 & 1.6x1012M☉,
and a time-varying potential, which includes the infall of a massive
Large Magellanic Cloud (LMC).
We were able to determine bulk proper motions for 73 systems, and we
consider 66 to be reliable measurements. For the first time, systemic
motions are presented for galaxies out to a distance of 1.4Mpc in the
NGC 3109 association. The inclusion of the infall of a massive LMC
significantly modifies the orbital trajectories of the objects, with
respect to orbit integration in static Milky-Way-only potentials, and
this leads to six galaxies likely being associated with the LMC, three
possibly being associated with it, and one recently captured object.
We discuss the results of the orbit integration in the context of the
relation of the galaxies to the system of Milky Way satellites,
implications for the too-big-to-fail problem, the impact on star
formation histories, and tidal disruption.
Description:
Probabilities of membership of the individual Gaia eDR3 sources to a
given dwarf galaxy or dwarf galaxy candidate. For each galaxy, we list
the Gaia eDR3 source ID, the Gaia eDR3 right ascension and
declination, and the probability of membership derived in the article.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
pmem.dat 105 645720 Probabilities of membership
--------------------------------------------------------------------------------
See also:
I/350 : Gaia EDR3 (Gaia Collaboration, 2020)
Byte-by-byte Description of file: pmem.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 15 A15 --- Galaxy Galaxy name
17- 35 I19 --- GaiaEDR3 GaiaEDR3 identifier
37- 58 F22.18 deg RAdeg [0.0/360.0] Right ascension (ICRS) at Ep=2016.0
60- 81 E22.17 deg DEdeg [-79.93/69.73] Declination (ICRS) at Ep=2016.0
83-105 E23.17 --- Pmemb [0/1]? Membership probability
--------------------------------------------------------------------------------
Acknowledgements:
Giuseppina Battaglia, gbattaglia80(at)googlemail.com
(End) Patricia Vannier [CDS] 04-Oct-2021