Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Production and detection of an axion dark matter echo   Electromagnetic radiation with angular frequency equal to half the axion mass
stimulates the decay of cold dark matter axions and produces an echo, i.e.
faint electromagnetic radiation traveling in the opposite direction. We propose
to search for axion dark matter by sending out to space a powerful beam of
microwave radiation and listening for its echo. We estimate the sensitivity of
this technique in the isothermal and caustic ring models of the Milky Way halo,
and find it to be a promising approach to axion, or axion-like, dark matter
detection.

32
The categories of this paper are: atom-ph
31
The categories of this paper are: ao-sci
22
The categories of this paper are: chao-dyn
33
The categories of this paper are: plasm-ph
12
The categories of this paper are: nucl-th
1
The categories of this paper are: cs
36
The categories of this paper are: cmp-lg
27
The categories of this paper are: comp-gas
13
The categories of this paper are: quant-ph
9
The categories of this paper are: nlin
10
The categories of this paper are: q-bio
30
The categories of this paper are: q-alg
24
The categories of this paper are: dg-ga
7
The categories of this paper are: hep-th
28
The categories of this paper are: alg-geom
20
The categories of this paper are: acc-phys