Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Coincidence of Nuclear Star Clusters and Active Galactic Nuclei   We study galaxies that host both nuclear star clusters and active galactic
nuclei (AGN) implying the presence of a massive black hole. We select a sample
of 176 galaxies with previously detected nuclear star clusters that range from
ellipticals to late-type spirals. We search for AGN in this sample using
optical spectroscopy and archival radio and X-ray data. We find galaxies of all
Hubble types and with a wide range of masses (10^9-11 solar masses) hosting
both AGN and nuclear star clusters. From the optical spectra, we classify 10%
of the galaxies as AGN and an additional 15% as composite, indicating a mix of
AGN and star-formation spectra. The fraction of nucleated galaxies with AGN
increases strongly as a function of galaxy and nuclear star cluster mass. For
galaxies with both a NC and a black hole, we find that the masses of these two
objects are quite similar. However, non-detections of black holes in Local
Group nuclear star clusters show that not all clusters host black holes of
similar masses. We discuss the implications of our results for the formation of
nuclear star clusters and massive black holes.

24
The categories of this paper are: dg-ga
28
The categories of this paper are: alg-geom
11
The categories of this paper are: hep-lat
9
The categories of this paper are: nlin
12
The categories of this paper are: nucl-th
1
The categories of this paper are: cs
5
The categories of this paper are: gr-qc
37
The categories of this paper are: supr-con
14
The categories of this paper are: math-ph
33
The categories of this paper are: plasm-ph
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The categories of this paper are: adap-org
25
The categories of this paper are: patt-sol
7
The categories of this paper are: hep-th
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The categories of this paper are: q-fin
10
The categories of this paper are: q-bio
23
The categories of this paper are: solv-int