Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The influence of gas on the structure of merger remnants   We present a large set of merger simulations of early-type disc galaxies with
mass ratios of 1:1 and 3:1 and 10% of the total disc mass in gas. In contrast
to the collisionless case equal-mass mergers with gas do not result in very
boxy remnants which is caused by the suppression of box orbits and the change
of the projected shape of minor-axis tube orbits in the more axisymmetric
remnants. The isophotal shape of 3:1 remnants and the global kinematic
properties of 1:1 and 3:1 remnants are only weakly affected by the presence of
gas. 1:1 remnants are slowly rotating whereas 3:1 remnants are fast rotating
and discy. The shape of the stellar LOSVD is strongly influenced by gas. The
LOSVDs of collisionless remnants have broad leading wings while their gaseous
counterparts show steep leading wings, more consistent with observations of
elliptical galaxies. We show that this change is also caused by the suppressed
populating of box orbits and it is amplified by the formation of extended gas
discs in the merger remnants. If elliptical galaxies have formed from mergers
our results indicate that massive, slowly rotating boxy elliptical galaxies can
not have formed from dissipative mergers of discs. Pure stellar (dry) mergers
are the more likely candidates. On the other hand lower mass, fast rotating and
discy ellipticals can have formed from dissipative (wet) mergers of early-type
discs. So far, only unequal-mass disc mergers with gas can successfully explain
their observed substructure. This is consistent with the revised morphological
classification scheme of increasing importance of gas dissipation when moving
from boxy ellipticals to discy ellipticals and then to spiral galaxies,
proposed by Kormendy & Bender (abbreviated).

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The categories of this paper are: nlin
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The categories of this paper are: chao-dyn
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The categories of this paper are: q-fin
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The categories of this paper are: plasm-ph
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The categories of this paper are: cs
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The categories of this paper are: patt-sol
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The categories of this paper are: solv-int
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The categories of this paper are: bayes-an
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The categories of this paper are: acc-phys
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The categories of this paper are: math-ph
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The categories of this paper are: nucl-th
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The categories of this paper are: nucl-ex
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The categories of this paper are: hep-lat
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The categories of this paper are: math
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The categories of this paper are: alg-geom
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The categories of this paper are: cond-mat