Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Constraints on Axion-Like Particles from X-ray Observations of NGC1275   Axion-like particles (ALPs) can induce localised oscillatory modulations in
the spectra of photon sources passing through astrophysical magnetic fields.
Ultra-deep Chandra observations of the Perseus cluster contain over $5 \times
10^5$ counts from the AGN of the central cluster galaxy NGC1275, and represent
a dataset of extraordinary quality for ALP searches. We use this dataset to
search for X-ray spectral irregularities from the AGN. The absence of
irregularities at the O(30%) level allows us to place leading constraints on
the ALP-photon mixing parameter $g_{a\gamma\gamma} \lesssim 1.4 - 4.0 \times
10^{-12} {\rm GeV}^{-1}$ for $m_a \lesssim 10^{-12}$ eV, depending on
assumptions on the magnetic field realisation along the line of sight.

19
The categories of this paper are: eess
33
The categories of this paper are: plasm-ph
35
The categories of this paper are: mtrl-th
5
The categories of this paper are: gr-qc
8
The categories of this paper are: hep-ex
30
The categories of this paper are: q-alg
15
The categories of this paper are: nucl-ex
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The categories of this paper are: q-fin
28
The categories of this paper are: alg-geom
34
The categories of this paper are: chem-ph
27
The categories of this paper are: comp-gas
22
The categories of this paper are: chao-dyn
36
The categories of this paper are: cmp-lg
12
The categories of this paper are: nucl-th
16
The categories of this paper are: stat
13
The categories of this paper are: quant-ph