Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A non-linear resonance model for the black hole and neutron star QPOs:
  theory supported by observations   Kilohertz Quasi-Periodic Oscillations (QPOs) have been detected in many
accreting X-ray binaries. It has been suggested that the highest QPO
frequencies observed in the modulation of the X-ray flux reflect a non-linear
resonance between two modes of accreting disk oscillation. This hypothesis
implies certain very general predictions, several of which have been borne out
by observations. Some of these follow from properties of non-linear
oscillators, while the others are specific to oscillations of fluid in strong
gravity. A 3:2 resonant ratio of frequencies can be clearly recognized in the
black-hole as well as in the neutron-star QPO data.

23
The categories of this paper are: solv-int
35
The categories of this paper are: mtrl-th
20
The categories of this paper are: acc-phys
15
The categories of this paper are: nucl-ex
30
The categories of this paper are: q-alg
26
The categories of this paper are: bayes-an
22
The categories of this paper are: chao-dyn
13
The categories of this paper are: quant-ph
7
The categories of this paper are: hep-th
10
The categories of this paper are: q-bio
16
The categories of this paper are: stat
2
The categories of this paper are: math
4
The categories of this paper are: cond-mat
34
The categories of this paper are: chem-ph
5
The categories of this paper are: gr-qc
21
The categories of this paper are: adap-org