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Abstract:
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In this dissertation, we presented galaxy mergers and the forming of stellar morphological
substructures. We assume a large spiral galaxy and dwarf galaxy which is a satellite
of the first one. We used N-body simulations to present different scenarios for the merger
of two galaxies, and after that, we analyzed the properties of formed structures. The
investigation of the formation of these structures and their properties is important for
understanding the dynamics and evolution of galaxies.
First, we did simulations where we investigated the influence of the properties of dwarf
galaxies on the forming structures. We tested: 1. morphology of the dwarf galaxy where
we used two models – dwarf with a disk and spheroidal dwarf galaxy; 2. inclination of the
orbit in the case of a very radial merger, because in that case, we have the formation of
the stellar shells and streams; 3. direction of rotation of the dwarf in the case of a dwarf
with a disk. In each case, after the merger, we have stellar shells and streams formed.
Morphology, inclination of the orbit, and direction of rotation have their influence on the
properties of formed substructures, and on the timescale of disruption of the remnant of
the dwarf.
In the case of the merger of Andromeda galaxy (M31) and dwarf galaxy, the satellite
of M31, we investigate the properties of the Giant Stellar Stream (GSS), as well as the
Northeast shell (NE) and West shell (W). The orientation of the GSS, distances, and
velocities of the GSS, NE, and W shells from our simulation are in agreement with the
observed one. For the first time, we explained the observed metallicity distribution in
these substructures. With a linearly decreasing gradient of the initial metallicity in the
dwarf galaxy before the merger, using Monte Carlo (MC) simulations, we successfully
explained the observed metallicity distribution in these substructures. These results are
a contribution to the investigation of metallicity gradients in dwarf galaxies which is
important for galaxy evolution in general. |