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dc.contributor.authorBanik, Indranil
dc.contributor.authorZhao, Hongsheng
dc.identifier.citationBanik , I & Zhao , H 2017 , ' Dynamical history of the Local Group in ΛCDM II − including external perturbers In 3D ' , Monthly Notices of the Royal Astronomical Society , vol. 467 , no. 2 , pp. 2180-2198 .
dc.identifier.otherPURE: 248968826
dc.identifier.otherPURE UUID: 616b692b-ba64-4745-b2d8-91e8aa73a076
dc.identifier.otherScopus: 85018315969
dc.identifier.otherORCID: /0000-0002-4123-7325/work/29708385
dc.identifier.otherWOS: 000398416700067
dc.descriptionIB is supported by a Science and Technology Facilities Council studentship.en
dc.description.abstractWe attempt to fit the observed radial velocities (RVs) of ~30 Local Group (LG) galaxies using a 3D dynamical model of it and its immediate environment within the context of the standard cosmological paradigm, ΛCDM. This extends and confirms the basic results of our previous axisymmetric investigation of the LG (MNRAS, 459, 2237). We find that there remains a tendency for observed RVs to exceed those predicted by our best-fitting model. The typical mismatch is slightly higher than in our 2D model, with a root mean square value of ~50 km/s. Our main finding is that including the 3D distribution of massive perturbing dark matter halos is unlikely to help greatly with the high velocity galaxy problem. Nonetheless, the 2D and 3D results differ in several other ways such as which galaxies' RVs are most problematic and the preferred values of parameters common to both models. The anomalously high RVs of several LG dwarfs may be better explained if the Milky Way (MW) and Andromeda (M31) were once moving much faster than in our models. This would allow LG dwarfs to gain very high RVs via gravitational slingshot encounters with a massive fast-moving galaxy. Such a scenario is possible in some modified gravity theories, especially those which require the MW and M31 to have previously undergone a close flyby. In a ΛCDM context, however, this scenario is not feasible as the resulting dynamical friction would cause a rapid merger.
dc.relation.ispartofMonthly Notices of the Royal Astronomical Societyen
dc.rights© 2017, the Author(s). This work has been made available online in accordance with the publisher’s policies. This is the final published version of the work, which was originally published at /
dc.subjectGalaxies: groups: individual: Local Groupen
dc.subjectGalaxy: kinematics and dynamicsen
dc.subjectDark Matteren
dc.subjectMethods: numerical: data analysisen
dc.subjectCosmology: cosmological parametersen
dc.subjectQB Astronomyen
dc.subjectQC Physicsen
dc.titleDynamical history of the Local Group in ΛCDM II − including external perturbers In 3Den
dc.typeJournal articleen
dc.description.versionPublisher PDFen
dc.contributor.institutionUniversity of St Andrews. School of Physics and Astronomyen
dc.description.statusPeer revieweden

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