Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Gas flows in galactic nuclei: observational constraints on BH-galaxy
  coevolution
2
The categories of this paper are: math
36
The categories of this paper are: cmp-lg
12
The categories of this paper are: nucl-th
8
The categories of this paper are: hep-ex
29
The categories of this paper are: funct-an
5
The categories of this paper are: gr-qc
34
The categories of this paper are: chem-ph
18
The categories of this paper are: econ
15
The categories of this paper are: nucl-ex
13
The categories of this paper are: quant-ph
23
The categories of this paper are: solv-int
19
The categories of this paper are: eess
37
The categories of this paper are: supr-con
21
The categories of this paper are: adap-org
10
The categories of this paper are: q-bio
17
The categories of this paper are: q-fin