Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Are dry mergers of Ellipticals the way to reconcile model predictions
  with the downsizing?   To show that the bulk of the star formation and the galaxy assembly should
occur simultaneously in order to reproduce at the same time the downsizing and
the chemical properties of present-day massive spheroids within one effective
radius.By means of chemical evolution models we create galactic building blocks
of several masses and different chemical properties. We then construct a sample
of possible merger histories going from a multiple minor merger scenario to a
single major merger event aimed at reproducing a single massive elliptical
galaxy. We compare our results against the mass-[Mg/Fe] and the
mass-metallicity relations. We found that a series of multiple dry-mergers (no
star formation in connection with the merger) involving building-blocks which
have been created ad hoc in order to satisfy the [Mg/Fe]-mass relation cannot
fit the mass-metallicity relation and viceversa. A major dry merger, instead,
does not worsen the agreement with observation if it happens between galaxies
which already obey to both the mass- or sigma-[Mg/Fe] and the mass-(sigma-)
metallicity relations. However, this process alone cannot explain the physical
reasons for these trends. Dry mergers alone cannot be the way to reconcile the
need of a more efficient star formation in the most massive galaxies with the
late time assembly suggested in the hierarchical paradigm in order to recover
the galaxy downsizing.

25
The categories of this paper are: patt-sol
4
The categories of this paper are: cond-mat
14
The categories of this paper are: math-ph
12
The categories of this paper are: nucl-th
10
The categories of this paper are: q-bio
8
The categories of this paper are: hep-ex
34
The categories of this paper are: chem-ph
20
The categories of this paper are: acc-phys
24
The categories of this paper are: dg-ga
2
The categories of this paper are: math
21
The categories of this paper are: adap-org
22
The categories of this paper are: chao-dyn
33
The categories of this paper are: plasm-ph
7
The categories of this paper are: hep-th
13
The categories of this paper are: quant-ph
15
The categories of this paper are: nucl-ex