Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Evidence for a gas-rich major merger in a proto-cluster at z=2.5   Gas-rich major mergers in high-redshift proto-clusters are important events,
perhaps leading to the creation of the slowly rotating remnants seen in the
cores of clusters in the present day. Here, we present a deep Jansky Very Large
Array observation of CO J = 1-0 emission line in a proto-cluster at z = 2.5,
USS1558-003. The target field is an extremely dense region, where 20 H-alpha
emitters (HAEs) are clustering. We have successfully detected the CO emission
line from three HAEs and discovered a close pair of red and blue CO-emitting
HAEs. Given their close proximity (~30 kpc), small velocity offset (~300 km/s),
and similar stellar masses, they could be in the early phase of a gas-rich
major merger. For the red HAE, we derive a total infrared luminosity of
L(IR)=5.1e12 Lsun using MIPS 24 um and radio continuum images. The L(IR)/L'(CO)
ratio is significantly enhanced compared to local spirals and high-redshift
disks with a similar CO luminosity, which is indicative of a starburst mode. We
find the gas depletion timescale is shorter than that of normal star-forming
galaxies regardless of adopted CO-H2 conversion factors. The identification of
such a rare event suggests that gas-rich major mergers frequently take place in
proto-clusters at z > 2 and may involve the formation processes of slow
rotators seen in local massive clusters.

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The categories of this paper are: quant-ph
31
The categories of this paper are: ao-sci
35
The categories of this paper are: mtrl-th
22
The categories of this paper are: chao-dyn
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The categories of this paper are: hep-lat
25
The categories of this paper are: patt-sol
2
The categories of this paper are: math
4
The categories of this paper are: cond-mat
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The categories of this paper are: q-fin
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The categories of this paper are: dg-ga
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The categories of this paper are: adap-org
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The categories of this paper are: nucl-th
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The categories of this paper are: nlin
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The categories of this paper are: hep-ph
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The categories of this paper are: math-ph
1
The categories of this paper are: cs