Bibcode
Kallivayalil, Nitya; Sales, Laura V.; Zivick, Paul; Fritz, Tobias K.; Del Pino, Andrés; Sohn, Sangmo Tony; Besla, Gurtina; van der Marel, Roeland P.; Navarro, Julio F.; Sacchi, Elena
Bibliographical reference
The Astrophysical Journal, Volume 867, Issue 1, article id. 19, 10 pp. (2018).
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11
2018
Journal
Citations
128
Refereed citations
118
Description
According to LCDM theory, hierarchical evolution occurs on all mass
scales, implying that satellites of the Milky Way should also have
companions. The recent discovery of ultra-faint dwarf galaxy candidates
in close proximity to the Magellanic Clouds provides an opportunity to
test this theory. We present proper motion (PM) measurements for 13 of
the 32 new dwarf galaxy candidates using Gaia data release 2. All 13
also have radial velocity measurements. We compare the measured 3D
velocities of these dwarfs to those expected at the corresponding
distance and location for the debris of a Large Magellanic Cloud (LMC)
analog in a cosmological numerical simulation. We conclude that four of
these galaxies (Hor1, Car2, Car3, and Hyi1) have come in with the
Magellanic Clouds, constituting the first confirmation of the type of
satellite infall predicted by LCDM. Ret2, Tuc2, and Gru1 have velocity
components that are not consistent within 3σ of our predictions
and are therefore less favorable. Hya2 and Dra2 could be associated with
the LMC and merit further attention. We rule out Tuc3, Cra2, Tri2, and
Aqu2 as potential members. Of the dwarfs without measured PMs, five of
them are deemed unlikely on the basis of their positions and distances
alone being too far from the orbital plane expected for LMC debris
(Eri2, Ind2, Cet2, Cet3, and Vir1). For the remaining sample, we use the
simulation to predict PMs and radial velocities, finding that Phx2 has
an overdensity of stars in DR2 consistent with this PM prediction.
Related projects
Galaxy Evolution in the Local Group
Galaxy formation and evolution is a fundamental Astrophysical problem. Its study requires “travelling back in time”, for which there are two complementary approaches. One is to analyse galaxy properties as a function of red-shift. Our team focuses on the other approach, called “Galactic Archaeology”. It is based on the determination of galaxy
Matteo
Monelli