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تسجيل مستخدم جديدThe role of tidal interactions in driving galaxy evolution
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We carry out a statistical analysis of galaxy pairs selected from chemical hydrodynamical simulations with the aim at assessing the capability of hierarchical scenarios to reproduce recent observational results for galaxies in pairs. Particularly, we analyse the effects of mergers and interactions on the star formation (SF) activity, the global mean chemical properties and the colour distribution of interacting galaxies. We also assess the effects of spurious pairs.
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Dwarf galaxies (M*<10^9 Msun) are key drivers of mass assembly in high mass galaxies, but relatively little is understood about the assembly of dwarf galaxies themselves. Using the textsc{NewHorizon} cosmological simulation (40 pc spatial resolution)
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We employ the earlier published proper motions of the newly discovered Antlia 2 dwarf galaxy derived from Gaia data to calculate its orbital distribution in the cosmologically recent past. Using these observationally motivated orbits, we calculate th
e effect of the Antlia 2 dwarf galaxy on the outer HI disk of the Milky Way, using both test particle and Smoothed Particle Hydrodynamics simulations. We find that orbits with low pericenters, $sim$ 10 kpc, produce disturbances that match the observed outer HI disk perturbations. We have independently recalculated the proper motion of the Antlia 2 dwarf from Gaia data and found a proper motion of $(mu_{alpha}cosdelta, mu_{delta}) = (-0.068,0.032) pm (0.023,-0.031)~rm mas/yr$, which agrees with results from Torrealba et al. (2019) within the errors, but gives lower mean pericenters, e.g., $sim$ 15 kpc for our fiducial model of the Milky Way. We also show that the Sagittarius dwarf galaxy interaction does not match the observed perturbations in the outer gas disk. Thus, Antlia 2 may be the driver of the observed large perturbations in the outer gas disk of the Galaxy. The current location of the Antlia 2 dwarf galaxy closely matches that predicted by an earlier dynamical analysis (Chakrabarti & Blitz 2009) of the dwarf that drove ripples in the outer Galaxy, and, in particular, its orbit is nearly coplanar to the Galactic disk. If the Antlia 2 dwarf galaxy is responsible for the perturbations in the outer Galactic disk, it would have a specific range of proper motions that we predict here; this can be tested soon with Gaia DR-3 and Gaia DR-4 data.
A key unresolved question is the role that galaxy mergers play in driving stellar mass growth over cosmic time. Recent observational work hints at the possibility that the overall contribution of `major mergers (mass ratios $gtrsim$1:4) to cosmic ste
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