Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Superradiant pion clouds around primordial black holes   We show that highly spinning primordial black holes of mass $M\sim 10^{12}$
kg, potentially born in a matter-dominated era after inflation, can produce
clouds of pions in their vicinity via the superradiant instability, with
densities up to that of nuclear matter. We discuss the electromagnetic
signatures of this process, via neutral pion decay and charged pion
annihilation into photons, computing in particular their contribution to the
isotropic gamma-ray background. This allows us to place upper bounds on the
abundance of such primordial black holes that are comparable to the ones
obtained from Hawking evaporation. We also discuss the possibility of directly
observing such clouds in high-redshift superclusters.

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The categories of this paper are: q-alg
13
The categories of this paper are: quant-ph
16
The categories of this paper are: stat
11
The categories of this paper are: hep-lat
25
The categories of this paper are: patt-sol
3
The categories of this paper are: physics
9
The categories of this paper are: nlin
36
The categories of this paper are: cmp-lg
2
The categories of this paper are: math
34
The categories of this paper are: chem-ph
21
The categories of this paper are: adap-org
7
The categories of this paper are: hep-th
8
The categories of this paper are: hep-ex
28
The categories of this paper are: alg-geom
37
The categories of this paper are: supr-con
27
The categories of this paper are: comp-gas