Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Galaxy Mergers at z>1 in the HUDF: Evidence for a Peak in the Major
  Merger Rate of Massive Galaxies   We present a measurement of the galaxy merger fraction and number density
from observations in the Hubble Ultra Deep Field for 0.5<z<2.5. We fit the
combination of broadband data and slitless spectroscopy of 1308 galaxies with
stellar population synthesis models to select merging systems based on a
stellar mass of >10^10 M_sol. When correcting for mass incompleteness, the
major merger fraction is not simply proportional to (1+z)^m, but appears to
peak at z_frac~=1.3+-0.4. From this merger fraction, we infer that ~42% of
massive galaxies have undergone a major merger since z~1. We show that the
major merger number density peaks at z_dens~1.2, which marks the epoch where
major merging of massive galaxies is most prevalent. This critical redshift is
comparable to the peak of the cosmic star formation rate density, and occurs
roughly 2.6 Gyr earlier in cosmic time than the peak in the number density of
X-ray selected active galactic nuclei. These observations support an indirect
evolutionary link between merging, starburst, and active galaxies.

17
The categories of this paper are: q-fin
21
The categories of this paper are: adap-org
34
The categories of this paper are: chem-ph
36
The categories of this paper are: cmp-lg
7
The categories of this paper are: hep-th
10
The categories of this paper are: q-bio
37
The categories of this paper are: supr-con
24
The categories of this paper are: dg-ga
18
The categories of this paper are: econ
13
The categories of this paper are: quant-ph
27
The categories of this paper are: comp-gas
22
The categories of this paper are: chao-dyn
15
The categories of this paper are: nucl-ex
32
The categories of this paper are: atom-ph
12
The categories of this paper are: nucl-th
23
The categories of this paper are: solv-int