Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: AGN feedback and the origin of the $\alpha$ enhancement in early type
  galaxies - insights from the GAEA model   We take advantage of our recently published model for Galaxy Evolution and
Assembly (GAEA) to study the origin of the observed correlation between
[$\alpha$/Fe] and galaxy stellar mass. In particular, we analyse the role of
radio mode AGN feedback, that recent work has identified as a crucial
ingredient to reproduce observations. In GAEA, this process introduces the
observed trend of star formation histories extending over shorter time-scales
for more massive galaxies, but does not provide a sufficient condition to
reproduce the observed $\alpha$ enhancements of massive galaxies. In the
framework of our model, this is possible only assuming that any residual star
formation is truncated for galaxies more massive than $10^{10.5}\,{\rm
M}_{\odot}$. This results, however, in even shorter star formation time-scales
for the most massive galaxies, that translate in total stellar metallicities
significantly lower than observed. Our results demonstrate that (i) trends of
[$\alpha$/Fe] ratios cannot be simply converted in relative time-scale
indicators, and (ii) AGN feedback cannot explain alone the positive correlation
between [$\alpha$/Fe] and galaxy mass/velocity dispersion. Reproducing
simultaneously the mass-metallicity relation and the $\alpha$ enhancements
observed poses a challenge for hierarchical models, unless more exotic
solutions are adopted such as metal-rich winds or a variable IMF.

19
The categories of this paper are: eess
24
The categories of this paper are: dg-ga
26
The categories of this paper are: bayes-an
13
The categories of this paper are: quant-ph
5
The categories of this paper are: gr-qc
9
The categories of this paper are: nlin
0
The categories of this paper are: hep-ph
1
The categories of this paper are: cs
29
The categories of this paper are: funct-an
15
The categories of this paper are: nucl-ex
27
The categories of this paper are: comp-gas
7
The categories of this paper are: hep-th
11
The categories of this paper are: hep-lat
34
The categories of this paper are: chem-ph
17
The categories of this paper are: q-fin
8
The categories of this paper are: hep-ex