Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Did NANOGrav see a signal from primordial black hole formation?
5
The categories of this paper are: gr-qc
30
The categories of this paper are: q-alg
2
The categories of this paper are: math
33
The categories of this paper are: plasm-ph
8
The categories of this paper are: hep-ex
34
The categories of this paper are: chem-ph
14
The categories of this paper are: math-ph
25
The categories of this paper are: patt-sol
11
The categories of this paper are: hep-lat
1
The categories of this paper are: cs
23
The categories of this paper are: solv-int
37
The categories of this paper are: supr-con
7
The categories of this paper are: hep-th
27
The categories of this paper are: comp-gas
16
The categories of this paper are: stat
18
The categories of this paper are: econ