Bibcode
Fritz, T. K.; Carrera, R.; Battaglia, G.; Taibi, S.
Referencia bibliográfica
Astronomy and Astrophysics, Volume 623, id.A129, 15 pp.
Fecha de publicación:
3
2019
Revista
Número de citas
45
Número de citas referidas
42
Descripción
A wealth of tiny galactic systems populates the surroundings of the
Milky Way. However, some of these objects might have originated as
former satellites of the Magellanic Clouds, in particular of the Large
Magellanic Cloud (LMC). Examples of the importance of understanding how
many systems are genuine satellites of the Milky Way or the LMC are the
implications that the number and luminosity-mass function of satellites
around hosts of different mass have for dark matter theories and the
treatment of baryonic physics in simulations of structure formation.
Here we aim at deriving the bulk motions and estimates of the internal
velocity dispersion and metallicity properties in four recently
discovered distant southern dwarf galaxy candidates, Columba I,
Reticulum III, Phoenix II, and Horologium II. We combined Gaia DR2
astrometric measurements, photometry, and new FLAMES/GIRAFFE
intermediate-resolution spectroscopic data in the region of the near-IR
Ca II triplet lines; this combination is essential for finding potential
member stars in these low-luminosity systems. We find very likely member
stars in all four satellites and are able to determine (or place limits
on) the bulk motions and average internal properties of the systems. The
systems are found to be very metal poor, in agreement with dwarf
galaxies and dwarf galaxy candidates of similar luminosity. Of these
four objects, we can only firmly place Phoenix II in the category of
dwarf galaxies because of its resolved high velocity dispersion (9.5
-4.4+6.8 km s-1) and intrinsic
metallicity spread (0.33 dex). For Columba I we also measure a clear
metallicity spread. The orbital pole of Phoenix II is well constrained
and close to that of the LMC, suggesting a prior association. The
uncertainty on the orbital poles of the other systems is currently very
large, so that an association cannot be excluded, except for Columba I.
Using the numbers of potential former satellites of the LMC identified
here and in the literature, we obtain for the LMC a dark matter mass of
M200 = 1.9 -0.9+1.3 ×
1011 M⊙.
Full Table 2 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr
(ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/623/A129Based
on ESO programs 096.B-0785(A) and 098.B-0419(A).
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